KR20210097212A - Csi reporting on small control channels - Google Patents

Abstract

Systems and methods are provided for channel state information (CSI) feedback on small control channels. In some embodiments, a method of operating a second node connected to a first node in a wireless communication network includes reporting CSI feedback to the first node on a physical channel. In some embodiments, this identifies a subset of codebook entries from the advanced CSI codebook of coefficients; select a codebook entry from the subset of codebook entries; This is accomplished by reporting the index of a codebook entry selected from a subset of codebook entries. This can allow for robust feedback and allows variable size co-phasing and beam index indicators to be carried on the channel. In addition, this may allow periodic feedback of advanced CSI in the existing physical uplink control channel (PUCCH) format 2.

Description

CSI Reporting on Small Control Channels {CSI REPORTING ON SMALL CONTROL CHANNELS}

Related applications

This application claims the benefit of Provisional Patent Application No. 62/455,440, filed on February 6, 2017, the entire disclosure of which is incorporated herein by reference.

technical field

This disclosure relates to reporting channel state information (CSI) feedback on a physical layer.

Because the Physical Uplink Control Channel (PUCCH) payload is limited, Long Term Evolution (LTE) uses CSI components (e.g., Channel Quality Indicators (CQI), precoding matrix indicators (PMI), rank indicators (RI), and CSI-RS resource indicators (CRI)]. Together with the PUCCH reporting mode and 'mode state', each reporting type defines the payload that can be carried in a given PUCCH transmission, which is the 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 36.213, Table 7.2.2- 3 is provided. In Rel-13, all PUCCH report types have payloads of 11 bits or less, and thus can all be carried in a single PUCCH format 2 transmission.

A system and method are provided for channel state information (CSI) feedback on small control channels. In some embodiments, a method of operating a second node connected to a first node in a wireless communication network includes reporting CSI feedback to the first node on a physical channel. In some embodiments, this identifies a subset of codebook entries from the advanced CSI codebook of coefficients; select a codebook entry from the subset of codebook entries; This is accomplished by reporting the index of a codebook entry selected from a subset of codebook entries. This may allow for robust feedback and may allow variable size co-phasing and beam index indicators to be carried on the channel. In addition, this may allow periodic feedback of advanced CSI in the existing physical uplink control channel (PUCCH) format 2.

In some embodiments, each entry in the codebook includes a vector or matrix. One or more elements of each entry in the codebook contain a scalar complex number. For any two different entries in the codebook, the norm between the matrix or vector difference between the two different entries in the codebook is greater than zero.

를 포함하고, L' 및 r은 양의 정수이다. 각각의 엔트리의 (L'-1)r 개의 요소 각각은 N개의 복소수 중 하나일 수 있는 스칼라 복소수를 포함한다.

이고,

는 상이한 코드북 엔트리들의 인덱스들이고,

는 행렬 또는 벡터 C의 프로베니우스 놈이다. 코드북은

개의 엔트리를 포함하고, 서브셋은

개의 엔트리 중 하나를 포함하고,

및

은 양의 정수이며, 서브셋 내의 각각의 엔트리는 인덱스에 의해 식별된다.In some embodiments, each entry in the codebook is identified by an index k. An entry in the codebook with index k is a vector or matrix of complex numbers with L' rows and r columns.

wherein L' and r are positive integers. Each of the (L'-1)r elements of each entry contains a scalar complex number that can be one of the N complex numbers.

ego,

are indices of different codebook entries,

is the Frobenius norm of a matrix or vector C. the code book

contains entries, the subset is

contains one of the entries,

and

is a positive integer, and each entry in the subset is identified by an index.

에 대해

이다.In some embodiments, the selected codebook entry for the case r=2 may be constructed from M=2 distinct variables, each variable may be one of K=N complex numbers, each entry in the subset

About

am.

에 대해

이다.In some embodiments, the selected codebook entry for the case r=2 may be constructed from M=3 distinct variables, with at least one entry in the subset

About

am.

개의 복소수 중 하나일 수 있고, 서브셋 내의 적어도 하나의 엔트리

에 대해

이다.In some embodiments, the selected codebook entry for the case r=2 may be constructed from M=4 distinct variables, each variable being

at least one entry in the subset,

About

am.

In some embodiments, the first node is a radio access node. In some embodiments, the second node is a wireless device. In some embodiments, the wireless communication network is a New Radio (NR) or fifth generation (5G) wireless communication network.

In some embodiments, a method of operation of a first node in a wireless communication network includes selecting a subset of codebook entries from an advanced CSI codebook of coefficients, selecting a codebook entry from the subset, and receiving an index of the selected codebook entry. thereby receiving CSI feedback from the second node on the physical channel.

In some embodiments, each entry in the codebook includes a vector or matrix. One or more elements of each entry in the codebook contain a scalar complex number. For any two different entries in the codebook, the norm between the matrix or vector difference between the two different entries in the codebook is greater than zero.

를 포함하고, L' 및 r은 양의 정수이다. 각각의 엔트리의 (L'-1)r개의 요소 각각은 N개의 복소수 중 하나일 수 있는 스칼라 복소수를 포함한다.

이고,

는 상이한 코드북 엔트리들의 인덱스들이고,

는 행렬 또는 벡터 C의 프로베니우스 놈이다. 코드북은

개의 엔트리를 포함하고, 서브셋은

개의 엔트리 중 하나를 포함하고,

및

은 양의 정수이며, 서브셋 내의 각각의 엔트리는 인덱스에 의해 식별된다.In some embodiments, each entry in the codebook is identified by an index k. An entry in the codebook with index k is a vector or matrix of complex numbers with L' rows and r columns.

wherein L' and r are positive integers. Each of the (L′-1)r elements of each entry contains a scalar complex number that can be one of the N complex numbers.

ego,

are indices of different codebook entries,

is the Frobenius norm of a matrix or vector C. the code book

contains entries, the subset is

contains one of the entries,

and

is a positive integer, and each entry in the subset is identified by an index.

에 대해

이다.In some embodiments, the selected codebook entry for the case r=2 may be constructed from M=2 distinct variables, each variable may be one of K=N complex numbers, each entry in the subset

About

am.

에 대해

이다.In some embodiments, the selected codebook entry for the case r=2 may be constructed from M=3 distinct variables, with at least one entry in the subset

About

am.

개의 복소수 중 하나일 수 있고, 서브셋 내의 적어도 하나의 엔트리

에 대해

이다.In some embodiments, the selected codebook entry for the case r=2 may be constructed from M=4 distinct variables, each variable being

at least one entry in the subset,

About

am.

In some embodiments, the first node is a radio access node. In some embodiments, the second node is a wireless device. In some embodiments, the wireless communication network is a new radio (NR) or fifth generation (5G) wireless communication network.

In some embodiments, the second node includes at least one processor and memory. The memory includes instructions executable by the at least one processor, whereby the second node is operable to report CSI feedback to the first node on a physical channel. In some embodiments, this is achieved by being operable to identify a subset of codebook entries from the advanced CSI codebook of coefficients, select a codebook entry from the subset of codebook entries, and report an index of the selected codebook entry from the subset of codebook entries. do.

In some embodiments, the second node identifies the subset of codebook entries from the advanced CSI codebook of coefficients; select a codebook entry from the subset of codebook entries; and a reporting module operable to report CSI feedback to the first node on a physical channel by being operable to report an index of a codebook entry selected from the subset of codebook entries.

In some embodiments, the first node includes at least one processor and memory. The memory includes instructions executable by the at least one processor, whereby the first node is operable to receive CSI feedback from the second node on the physical channel. In some embodiments, this is achieved by selecting a subset of codebook entries from the advanced CSI codebook of coefficients, selecting a codebook entry from the subset, and operable to receive an index of the selected codebook entry.

In some embodiments, the first node selects a subset of codebook entries from an advanced CSI codebook of coefficients; codebook entries are selected from the subset; and a receiving module operable to receive the CSI feedback for the first node on the physical channel by being operable to receive the index of the selected codebook entry.

In some embodiments, in Third Generation Partnership Project (3GPP), for advanced CSI reporting in Rel-14, W ₁ is reported as a payload of 13 bits, while W ₂ is 6 bits for rank=1 or It is reported as a payload of 12 bits for rank=2. This implicitly assumes aperiodic reporting on a Physical Uplink Shared Channel (PUSCH) where the feedback payload is not constrained. However, for periodic CSI reporting on a Physical Uplink Control Channel (PUCCH), Long Term Evolution (LTE) currently supports only CSI feedback of PUCCH format 2 with a payload of 11 bits. Since the payload is larger than 11 bits, neither W ₁ or W ₂ (for rank-2) can be reported directly in a single PUCCH format 2 transmission.

_{The indications of W 1} and W ₂ for the advanced CSI codebook in 3GPP are (at least in some cases) larger than can be supported in PUCCH format 2, and thus advanced CSI is not yet adequately supported for PUCCH reporting.

Some embodiments disclosed herein relate to:

Link the two co-phasing vectors (one for each layer) of rank 2 so that the two vectors are orthogonal, and write the Quadrature Phase-Shift Keying (QPSK) alphabet for each co-phasing coefficient. subsampling _{W 2} by using, resulting in 4 bits for _{W 2 feedback.}

Binary Phase-Shift Keying (BPSK) alphabet using the same co-phasing coefficients for two polarizations with independent co-phasing vectors in rank 2 and for each co-phasing coefficient subsampling _{W 2} by using , resulting in 4 bits for _{W 2 feedback.}

Feeding back both rank indicator and beam count indicator in PUCCH transmission to allow robust feedback, and to allow variable size co-paging and beam index indicators to be carried on PUCCH.

_{Subsampling W 2} by linking the two co-phasing vectors of rank 2 (one for each layer) so that the two vectors are orthogonal and using the QPSK alphabet for each co-phasing coefficient, W ₂ What causes 4 bits for feedback.

_{Subsampling W 2} by using the same co-phasing coefficients for the two polarizations with independent co-phasing vectors at rank 2 and using the BPSK alphabet for each co-phasing coefficient, so that the W ₂ feedback What causes 4 bits for .

Feeding back both rank indicator and beam count indicator in PUCCH transmission to allow robust feedback, and to allow variable size co-paging and beam index indicators to be carried on PUCCH.

Some embodiments relate to configuring a feedback mechanism for reporting CSI feedback on small payload channels, such as PUCCH, while still maintaining sufficient CSI accuracy and reliability. In some embodiments, this is achieved through various mechanisms including reporting subsets of codebooks, using variable size indicators for CSI reporting components, and multiplexing compatible CSI components together. These embodiments allow periodic feedback of advanced CSI in the existing PUCCH format 2.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and form a part of this specification, illustrate various aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.
1 illustrates a wireless communication system in accordance with some embodiments.
2 illustrates a downlink physical resource as may be used in a Long Term Evolution (LTE) wireless communication system.
3 shows a time domain structure that can be used in an LTE wireless communication system.
4 shows a downlink subframe that may be used in an LTE wireless communication system.
5 illustrates an uplink L1/L2 control signaling transmission on a physical uplink control channel (PUCCH) in accordance with some embodiments of the present disclosure.
6 illustrates a transmission structure of a precoded spatial multiplexing mode that may be used in an LTE wireless communication system according to some embodiments of the present disclosure.
7 illustrates an exemplary comparison of subband and wideband in accordance with some embodiments of the present disclosure.
8 illustrates an exemplary two-dimensional antenna array in accordance with some embodiments of the present disclosure.
9 is an oversampled discrete Fourier transform (DFT) with _{(N 1} ,N ₂ )=(4,2) and (O ₁ ,O ₂ )=(4,4) in accordance with some embodiments of the present disclosure; ) shows an example of the beams.
10A, 11A, 12A, and 13A illustrate procedures for reporting CSI feedback on a physical channel according to some embodiments of the present disclosure.
10B, 11B, 12B, and 13B illustrate procedures for receiving CSI feedback on a physical channel according to some embodiments of the present disclosure.
14 and 15 show an exemplary embodiment of a wireless device in accordance with some embodiments of the present disclosure.
16-18 show exemplary embodiments of a radio network node in accordance with some embodiments of the present disclosure.

The embodiments presented below represent information enabling those skilled in the art to practice the embodiments, and show the best mode of carrying out the embodiments. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and recognize applications of these concepts not specifically mentioned herein. It is to be understood that these concepts and applications fall within the scope of the present disclosure.

Note that although terminology from 3GPP LTE is used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the systems mentioned above. New Radio (NR) (i.e., fifth generation (5G)], Wideband Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB), and Global System (GSM) for Mobile Communications) may also benefit from using the ideas covered in this disclosure.

Also, terms such as evolved or enhanced NodeB (eNodeB) and User Equipment (UE) should be considered non-limiting and do not imply a specific hierarchical relationship between the two; Note that in general "eNodeB" can be considered as device 1 and "UE" can be considered as device 2, these two devices communicating with each other over a certain radio channel. Here, while wireless transmissions in the downlink are discussed in detail, some embodiments of the present disclosure are equally applicable in the uplink.

In this regard, FIG. 1 depicts an example of a wireless system 10 (eg, a cellular communication system) in which embodiments of the present disclosure may be implemented. The wireless system 10 includes a first node 12 which in this example is a radio access node. However, the first node 12 is not limited to a radio access node and may be any other device such as a general radio node allowing communication within a radio network, including the wireless device described below. The radio access node 12 is connected to other nodes, such as a wireless device, or other access nodes, such as the second node 14, within a coverage area 16 (eg, a cell) of the radio access node 12 . provides wireless access to In some embodiments, the second node 14 is a Long Term Evolution User Equipment (LTE UE). Note that in this specification, the term “UE” is used in its broad sense to mean any wireless device. As such, the terms "wireless device" and "UE" are used interchangeably herein.

LTE uses Orthogonal Frequency-Division Multiplexing (OFDM) in the downlink, and Discrete Fourier Transform (DFT)-spread OFDM in the uplink. Thus, the basic LTE downlink physical resource can be viewed as a time-frequency grid as shown in FIG. 2 , where each resource element corresponds to one OFDM subcarrier during one OFDM symbol interval.

3 shows a time domain structure that can be used in an LTE wireless communication system. In the time domain, LTE downlink transmissions are organized into radio frames of 10 ms, and each radio frame consists _{of 10 subframes} of the same size of length T subframe = 1 ms.

Moreover, resource allocation in LTE is typically described in terms of resource blocks, where a resource block corresponds to one slot (0.5 ms) in the domain domain and 12 contiguous subcarriers in the frequency domain. Resource blocks are numbered in the frequency domain, starting with zero at either end of the system bandwidth.

Downlink transmissions are dynamically scheduled; That is, in each subframe, the base station transmits control information on which terminal data is transmitted and in which resource block data is transmitted in the current downlink subframe. This control signaling is typically sent in the first 1, 2, 3 or 4 OFDM symbols within each subframe. A downlink system with three OFDM symbols as control is shown in FIG. 4 .

LTE uses Hybrid Automatic Repeat Requests (HARQ), where after receiving downlink data in a subframe, the terminal tries to decode it, and whether the decoding was successful (ACK) or not (NACK) ) to the base station. If the decoding attempt fails, the base station may retransmit erroneous data.

Uplink control signaling from the terminal to the base station consists of:

HARQ acknowledgments for the received downlink data;

terminal reports related to downlink channel conditions, used as an aid to downlink scheduling; and

Scheduling requests indicating that the mobile terminal needs uplink resources for uplink data transmissions.

To provide frequency diversity, these frequency resources are frequency hopping at slot boundaries, i.e. one “resource” is 12 subcarriers at the top of the spectrum in the first slot of the subframe, and the second in the subframe. It consists of resources of the same size in the lower part of the spectrum during the slot and vice versa. If more resources are needed for uplink L1/L2 control signaling, e.g. for very large overall transmission bandwidth to support multiple users, additional resource blocks may be allocated next to previously allocated resource blocks. there is. 5 shows uplink L1/L2 control signaling transmission on a physical uplink control channel (PUCCH).

As mentioned above, uplink L1/L2 control signaling includes HARQ acknowledgments, channel state information, and scheduling requests. Although different combinations of these message types are possible as further described below, in order to explain the structure for this case, it is advantageous to first discuss each type of individual transmission, starting with HARQ and Scheduling Requests. There are five formats defined for PUCCH in Rel-13, each of which can carry a different number of bits. Against this background, PUCCH formats 2 and 3 are most relevant.

UEs may report Channel State Information (CSI) to provide an estimate of channel properties at the UE to the eNodeB to aid in channel-dependent scheduling. Such channel properties are those that tend to change with fading or interference of the channel, such as the relative gain and phase of the channel between antenna elements, the signal-to-interference and noise ratio (SINR) in a given subframe, and the like. Such CSI feedback is used to adapt Multiple-Input Multiple-Output (MIMO) precoding and modulation and coding conditions. LTE is a Received Signal Strength Indicator (RSSI), Reference Signal Received Power (RSRP), and Reference Signal Received Quality (RSRQ) of channel properties such as It provides a different measure; These are long-term properties that are not used to adapt MIMO transmission or to select modulation and coding states, and therefore are not considered CSI in the context of this disclosure.

The CSI report consists of multiple bits per subframe transmitted in the Uplink Control Information (UCI) report. PUCCH format 1, which can cover up to 2 bits of information per subframe, obviously cannot be used for this purpose. The transmission of CSI report on PUCCH in Rel-13 is instead covered by PUCCH formats 2, 3, 4 and 5, which can cover multiple information bits per subframe.

PUCCH format 2 resources are semi-statically configured. A Format 2 report can carry a payload of up to 11 bits. Variations of format 2 are formats 2a and 2b, which also carry 1 and 2 bits of HARQ-ACK information for a normal cyclic prefix, respectively. For extended cyclic prefix, PUCCH format 2 may also carry HARQ-ACK information. For the sake of simplicity, they are all referred to herein as Format 2.

PUCCH format 3 is designed to support larger HARQ-ACK payloads and can carry up to 10 or 20 HARQ-ACK bits for FDD and TDD, respectively. Also, it can carry Scheduling Requests (SR), thus supporting up to 21 bits in total. PUCCH format 3 may also carry CSI. PUCCH formats 4 and 5 still carry larger payloads.

Because PUCCH payloads are limited, LTE uses CSI components (e.g., Channel Quality Indicators (CQI), Precoding Matrix Indicators (PMI), rank indicators ( RI), and CRI-RS resource indicators (CRI)]. Together with the PUCCH reporting mode and 'mode state', each report type defines the payload that can be carried in a given PUCCH transmission, which is given in Table 7.2.2-3 of 3GPP TS 36.213. In Rel-13, since all PUCCH report types have payloads of 11 bits or less, they can all be carried in a single PUCCH format 2 transmission.

In Rel-13 LTE, various CSI reporting types are defined.

Type 1 report supports CQI feedback for subbands selected by the UE.

Type 1a reports support subband CQI and second PMI feedback.

Type 2, Type 2b and Type 2c reports support wideband CQI and PMI feedback.

Type 2a reports support wideband PMI feedback.

Type 3 reports support RI feedback.

Type 4 reports support broadband CQI.

Type 5 reports support RI and wideband PMI feedback.

Type 6 reports support RI and PMI feedback.

Type 7 reports support CRI and RI feedback.

Type 8 reports support CRI, RI and wideband PMI feedback.

Type 9 reports support CRI, RI and PMI feedback.

Type 10 reports support CRI feedback.

These report types are transmitted on the PUCCH with periods and offsets (subframe units) determined according to whether CQI, Class A first PMI, RI or CRI is carried by the report type.

Table 1 below shows subframes when various report types are transmitted, assuming that wideband CSI reports are used with a single CSI subframe set. For subband reporting and multiple subframe sets, similar mechanisms are used.

Note that the CRI is for a case where more than one CSI-RS resource is configured. (as defined in 3GPP TS 36.213 and 36.331) as follows:

는 시스템 프레임 번호이다

is the system frame number

는 라디오 프레임 내의 슬롯 번호이다.

is a slot number in a radio frame.

는 상위 계층 파라미터 cqi-pmi-ConfigIndex에 의해 설정된 서브프레임들 내에서의 주기성이다.

is the periodicity within subframes set by the higher layer parameter cqi-pmi-ConfigIndex.

는 상위 계층 파라미터 cqi-pmi-ConfigIndex에 의해 설정된 서브프레임 내의 오프셋이다.

is the offset within the subframe set by the higher layer parameter cqi-pmi-ConfigIndex.

은 상위 계층 파라미터 periodicityFactorWB에 의해 설정된다.

is set by the upper layer parameter periodicityFactorWB.

는 상위 계층 파라미터 ri-ConfigIndex에 의해 설정된 서브프레임들 내에서의 주기성 배수(periodicity multiple)이다

is a periodicity multiple within the subframes set by the higher layer parameter ri-ConfigIndex

는 상위 계층 파라미터 ri-ConfigIndex에 의해 설정된 서브프레임들 내에서의 오프셋이다.

is an offset within subframes set by the higher layer parameter ri-ConfigIndex.

는 상위 계층 파라미터 cri-ConfigIndex에 의해 설정된 서브프레임들 내에서의 주기성 배수이다.

is a periodicity multiple within subframes set by the higher layer parameter cri-ConfigIndex.

서브프레임들의 기본 주기성을 가지며, CQI들은 이러한 레이트로 보고될 수 있다. 오프셋

는 RI가 CQI와 동일한 주기성의 상이한 서브프레임 시프트들을 갖는 것을 허용할 수 있으므로, RI가 구성된 경우, 그것은

=1을 구성함으로써 CQI와 동일한 레이트로 보고될 수 있다. 한편, 클래스 A 제1 PMI는 CQI와 함께 시간 다중화되고, 여기서 클래스 A 제1 PMI는 CQI의

전송들 중 하나에서 CQI 대신에 전송된다. CRI는 유사한 방식으로 RI와 시간 다중화되는데, 즉 CRI는 RI의

전송들 중 하나에서 RI 대신에 전송된다.PUCCH CSI report

With a basic periodicity of subframes, CQIs may be reported at this rate. offset

may allow RI to have different subframe shifts of the same periodicity as CQI, so if RI is configured, it

By configuring =1, it can be reported at the same rate as the CQI. On the other hand, the class A first PMI is time multiplexed with the CQI, where the class A first PMI is the

In one of the transmissions is sent instead of the CQI. CRIs are time multiplexed with RIs in a similar way, that is, CRIs are

In one of the transmissions is sent instead of the RI.

In addition, PUCCH format 3 can carry ACK/NACK and CSI in the same PUCCH transmission, but the CSI must come from only one serving cell. In addition, in Rel-13, the UE transmits CSI only in PUCCH format 3 when transmitting ACK/NACK. If there is no ACK/NACK to be transmitted in a given subframe and CSI is to be transmitted on PUCCH, the UE will use PUCCH format 2 in that subframe.

LTE control signaling is embedded in (PUSCH) on a Physical Downlink Control Channel (PDCCH), an Enhanced Physical Downlink Control Channel (EPDCCH), or PUCCH, Medium Access Control (MAC) ) in control elements ('MAC CE') or in radio resource control (RRC) signaling. Each of these mechanisms is customized to convey a particular kind of control information. As used herein, a control channel may refer to any of these mechanisms. Additionally, a transmission on a control channel may refer to a separate transmission carrying information, or a portion of a transmission carrying specific information.

Control information carried on PDCCH, EPDCCH, PUCCH or embedded in PUSCH is physical layer related control information such as downlink control information (DCI) and uplink control information (UCI) as described in 3GPP TS 36.211, 36.212 and 36.213 am. DCI is generally used to instruct the UE to perform a predetermined physical layer function while providing information necessary to perform the function. UCI generally provides the network with necessary information such as HARQ-ACK, scheduling request (SR), channel state information (CSI) including CQI, PMI, RI and/or CRI. UCI and DCI are designed to support rapidly changing parameters, including those that may be transmitted on a subframe basis, and thus may change depending on a fast fading radio channel. Since UCI and DCI can be transmitted in every subframe, the UCI or DCI corresponding to a given cell tends to be on the order of several tens of bits to limit the amount of control overhead.

Control information carried in MAC CEs is carried in MAC headers on uplink and downlink shared transport channels (UL-SCH and DL-SCH) as described in 3GPP TS 36.321. Since the MAC header does not have a fixed size, control information in MAC CEs can be transmitted when it is needed and does not necessarily represent a fixed overhead. Also, MAC CEs can efficiently carry larger control payloads because they are carried on UL-SCH or DL-SCH transport channels, which benefit from link adaptation, HARQ and can be turbo coded (on the other hand, Rel-13 cannot have UCI and DCI). MAC CEs are used to perform repetitive tasks using a fixed parameter set, such as maintaining timing advance or buffer status reports, but these tasks generally do not require transmission of MAC CEs in subframe units. Consequently, channel state information related to fast fading radio channels such as PMIs, CQIs, RIs and CRIs is not carried in MAC CEs in Rel-13.

Dedicated RRC control information is also carried over UL-SCHs and DL-SCHs using Signaling Radio Bearer (SRB) as discussed in 3GPP TS 36.331. Consequently, it can also efficiently carry large control payloads. However, SRBs are generally not intended for very frequent transmission of large payloads and need to be available to support less frequent signaling that must be transmitted highly reliably, such as for mobility procedures including handover. . Therefore, like MAC, RRC signaling does not carry channel state information related to fast fading radio channels such as PMIs, CQIs, RIs and CRIs in Rel-13. In fact, this kind of CSI is carried only in PUSCHs or UCI signaling on PUCCHs.

Multi-antenna technology can significantly increase data rates and reliability of a wireless communication system. Performance is particularly improved if both the transmitter and receiver have multiple antennas, which results in multiple input and multiple output (MIMO) communication channels. These systems and/or related technologies are commonly referred to as MIMO.

The LTE standard is currently evolving with improved MIMO support. A key component of LTE is the support of MIMO antenna deployments and MIMO-related technologies. LTE Release 12 supports an 8-layer spatial multiplexing mode for 8 Tx antennas with channel dependent precoding. Spatial multiplexing mode targets high data rates in good channel conditions. A description of the spatial multiplexing operation is provided in FIG. 6 .

프리코더 행렬 W가 곱해지고, 이는 (N_T 안테나 포트들에 대응하는) N_T 차원 벡터 공간의 서브스페이스에서 송신 에너지를 분배하는 역할을 한다. 프리코더 행렬은 전형적으로 가능한 프리코더 행렬들의 코드북으로부터 선택되고, 주어진 수의 심볼 스트림들에 대해 코드북 내의 고유 프리코더 행렬을 특정하는 PMI에 의해 전형적으로 지시된다. s 내의 r개의 심볼들은 계층에 각각 대응하고, r은 전송 랭크로 지칭된다. 이러한 방식으로, 복수의 심볼이 동일한 시간/주파수 리소스 요소(TFRE)를 통해 동시에 전송될 수 있기 때문에, 공간 다중화가 달성된다. 심볼들의 수 r은 전형적으로 현재 채널 속성들에 맞도록 적응된다.As can be seen in Figure 6, the information carrying symbol vector s has

The precoder matrix W is multiplied, which serves to distribute the transmit energy in the subspace of the _{N T} dimensional vector space (corresponding to the _{N T antenna ports).} The precoder matrix is typically selected from a codebook of possible precoder matrices, and is typically indicated by a PMI specifying a unique precoder matrix in the codebook for a given number of symbol streams. The r symbols in s each correspond to a layer, and r is referred to as a transmission rank. In this way, spatial multiplexing is achieved because multiple symbols can be transmitted simultaneously on the same time/frequency resource element (TFRE). The number r of symbols is typically adapted to fit the current channel properties.

벡터 y_n은 다음에 의해 모델링된다:LTE uses OFDM in the downlink (and DFT precoded OFDM in the uplink), and thus the received received TFRE for a particular TFRE on subcarrier n (or alternatively data TFRE number n).

The vector y _n is modeled by:

은 랜덤 프로세스의 실현들로서 얻어진 잡음/간섭 벡터이다. 프리코더

는 주파수에 걸쳐 일정하거나 주파수 선택성(frequency selective)인 광대역 프리코더일 수 있다.here,

is the noise/interference vector obtained as realizations of the random process. precoder

may be a wideband precoder that is constant across frequency or frequency selective.

는 종종

MIMO 채널 행렬

의 특성들에 일치하도록 선택되고, 이는 소위 채널 종속 프리코딩을 야기한다. 이는 또한 통상적으로 폐쇄 루프 프리코딩(closed-loop precoding)이라고도 지칭되며, 본질적으로 송신되는 에너지 중 많은 부분을 UE에 전달한다는 의미에서 강한 서브스페이스 내에 송신 에너지를 집중시키려고 노력한다. 추가로, 프리코더 행렬은 또한 채널을 직교화하기 위해 노력하도록 선택될 수 있는데, 이는 UE에서의 적절한 선형 등화 후에, 계층간 간섭이 감소됨을 의미한다.precoder matrix

is often

MIMO Channel Matrix

is chosen to match the characteristics of , which leads to so-called channel dependent precoding. This is also commonly referred to as closed-loop precoding, and essentially tries to concentrate the transmit energy within a strong subspace in the sense of transferring a large portion of the transmitted energy to the UE. In addition, the precoder matrix may also be chosen to try to orthogonalize the channel, which means that after proper linear equalization at the UE, inter-layer interference is reduced.

를 선택하는 하나의 예시적인 방법은 가정된 등가 채널(hypothesized equivalent channel)의 프로베니우스 놈(Frobenius norm)을 최대화하는

를 선택하는 것일 수 있다:UE precoder matrix

One exemplary method of selecting

may be to choose:

는 아마도 아래에 설명되는 바와 같은 CSI-RS로부터 도출되는 채널 추정치이다.

는 인덱스 k를 갖는 가정된 프리코더 행렬이다.

는 가정된 등가 채널이다.here,

is the channel estimate derived from the CSI-RS, perhaps as described below.

is the hypothesized precoder matrix with index k.

is the assumed equivalent channel.

In the context of CSI feedback, a subband is defined as a number of contiguous pairs of physical resource blocks (PRBs). In LTE, the subband size (ie, the number of adjacent PRB pairs) depends on the system bandwidth, whether CSI reporting is configured periodically or aperiodically, and the type of feedback (ie, higher layer configured feedback). configured, or whether UE-selected subband feedback is configured]. An example illustrating the difference between subband and broadband is shown in FIG. 7 . In the example, the subband consists of 6 contiguous PRBs. Note that in Fig. 7, only two subbands are shown for simplicity of illustration. In general, all PRB pairs within the system bandwidth are partitioned into different subbands, where each subband consists of a fixed number of PRB pairs. In contrast, wideband entails all PRB pairs within the system bandwidth. As mentioned above, when the UE is configured to report wideband PMI by the NodeB, the UE can feed back a single precoder that takes measurements from all PRB pairs within the system bandwidth. Alternatively, if the UE is configured to report subband PMI, the UE may feed back multiple precoders, one precoder per subband. Additionally, for subband precoders, the UE may also feedback wideband PMI.

In closed loop precoding for LTE downlink, the UE sends to the eNodeB a recommendation of a precoder suitable for use, based on channel measurements in the forward link (downlink). The eNB configures the UE to provide feedback according to the transmission mode of the UE, transmits the CSI-RS, and configures the UE to use the measurements of the CSI-RS to feed back recommended precoding matrices that the UE selects from the codebook. do. A single precoder that is supposed to cover a wide bandwidth can be fed back (wideband precoding). It may also be advantageous to match the frequency deviations of the channel and instead feed a frequency-selective precoding report back to several precoders, for example one per subband. This is an example of a more general case of channel state information feedback, which also encompasses feeding back information other than the precoders recommended to assist the eNodeB in subsequent transmission to the UE. Such other information includes the CQI as well as the transmit RIs.

의 열들의 수에 반영된다. 효율적인 성능을 위해, 채널 속성들과 일치하는 전송 랭크가 선택되는 것이 중요하다.Given the CSI feedback from the UE, the eNodeB determines the transmission parameters it wants to use to transmit to the UE, including the precoding matrix, the transmission rank, and the modulation and coding state (MCS). These transmission parameters may be different from those recommended by the UE. Thus, the rank indicator and MCS may be signaled in DCI, the precoding matrix may be signaled in DCI, or the eNodeB may transmit a demodulation reference signal from which the equivalent channel may be measured. The transmission rank, and hence the number of spatially multiplexed layers, is determined by the precoder

is reflected in the number of columns in For efficient performance, it is important that a transmission rank that matches the channel properties is selected.

과 코드북의 프리코딩 행렬 사이의 최상의 일치를 찾기 위해 UE에 의해 사용된다. 채널

은 TM9 및 TM10에 대해 다운링크에서 전송된 비-제로 전력 CSI 기준 신호(NZP CSI-RS)에 기초하여 추정된다.In closed loop MIMO transmission schemes such as TM9 and TM10, the UE estimates the downlink CSI and feeds it back to the eNodeB. The eNB sends downlink data to the UE using the fed back CSI. CSI consists of transmit RI, PMI and CQI. The codebook of precoding matrices is based on a certain criterion, e.g. UE throughput, the estimated downlink channel

and used by the UE to find the best match between the precoding matrix of the codebook. channel

is estimated based on the non-zero power CSI reference signal (NZP CSI-RS) transmitted in the downlink for TM9 and TM10.

의 추정이 직접 피드백되는 것은 아니므로, 이는 암시적 CSI 피드백이라고도 지칭된다. CQI/RI/PMI는 어느 보고 모드가 구성되는지에 따라 광대역 또는 부대역일 수 있다.CQI/RI/PMI together provide the downlink channel status to the UE.

Since the estimation of α is not directly fed back, it is also referred to as implicit CSI feedback. CQI/RI/PMI may be wideband or subband depending on which reporting mode is configured.

The RI corresponds to the recommended number of streams to be spatially multiplexed and thus transmitted in parallel over the downlink channel. The PMI identifies a recommended precoding matrix codeword (in a codebook containing precoders with a number of rows equal to the number of CSI-RS ports) for transmission, which is related to the spatial characteristics of the channel. CQI represents the recommended transport block size (i.e. code rate), and LTE is one or two simultaneous (in different layers) of transport blocks (i.e. individually encoded information blocks) within a subframe. Supports sending enemy transmissions to the UE. Thus, there is a relationship between the CQI and the SINR of the transport block or spatial stream(s) in which the blocks are transmitted.

In LTE up to Release 13, a codebook of up to 16 antenna ports was defined. Both one-dimensional (2D) and two-dimensional (2D) antenna arrays are supported. For UEs of LTE Release 12 and earlier, only codebook feedback for 1D port layout with 2, 4 or 8 antenna ports is supported. Accordingly, the codebook is designed assuming that these ports are arranged in a one-dimensional straight line. In LTE Rel-13, for the case of 8, 12 or 16 antenna ports, codebooks for 2D port layouts have been defined. In addition, a codebook for 1D port layout for the case of 16 antenna ports was also specified in LTE Rel-13.

In LTE Rel-13, two types of CSI reporting have been introduced: class A and class B. In class A CSI reporting, the UE measures and reports CSI based on a new codebook for a configured 2D antenna array with 8, 12 or 16 antenna ports. A class A codebook is defined by five parameters, namely ( N1 , N2 , Q1 , Q2 , CodebookConfig ), where (N1, N2) is the number of antenna ports in one dimension and two dimensions, respectively. (Q1, Q2) are the DFT oversampling factors for 1D and 2D, respectively. CodebookConfig ranges from 1 to 4, defining four different ways to form a codebook. For CodebookConfig=1, the PMI corresponding to a single 2D beam is fed back for the entire system bandwidth, whereas for CodebookConfig={2,3,4}, PMIs corresponding to 4 2D beams are fed back, each unit The inverse may relate to different 2D beams. CSI consists of RI, PMI and CQI or CQIs similar to CSI reporting prior to Rel-13.

In class B CSI reporting, in one scenario ( _{also referred to as “K CSI-RS} > 1”), the eNB may preform multiple beams in one antenna dimension. There may be multiple ports (1, 2, 4 or 8 ports) within each beam of different antenna dimensions. A “beamformed” CSI-RS is transmitted along each beam. The UE first selects the best beam from the group of configured beams and then measures the CSI within the selected beam based on the pre-Release 13 legacy LTE codebook for 2, 4 or 8 ports. Next, the UE reports back the selected beam index and CSI corresponding to the selected beam. In another scenario ( _{also referred to as “K CSI-RS} =1”), the eNB may form up to 4 (2D) beams in each polarization, and the “beamformed” CSI-RS along each beam. is sent The UE measures the CSI in the “beamformed” CSI-RS and feeds back the CSI based on the new class B codebook for 2, 4 or 8 ports.

In LTE Release-10, a new reference symbol sequence was introduced for the purpose of estimating downlink channel state information, ie, CSI-RS. CSI-RS provides several advantages over having CSI feedback based on the CRS used for that purpose in previous releases. First, the CSI-RS is not used for demodulation of the data signal, and therefore does not require the same density (ie, the overhead of the CSI-RS is substantially less). Second, CSI-RS provides a much more flexible means for configuring CSI feedback measurements (eg, which CSI-RS resource to measure for may be configured in a UE specific manner).

가 전송되는 경우, UE가 전송된 신호와 수신된 신호 사이의 결합(즉, 유효 채널)을 추정할 수 있음을 암시한다. 그러므로, 전송에서 가상화가 수행되지 않는 경우, 수신된 신호

는 다음과 같이 표현될 수 있고:By measuring the CSI-RS transmitted from the eNodeB, the UE can estimate the effective channel the CSI-RS traverses, including the radio propagation channel and antenna gains. At more mathematical precision, this is a known CSI-RS signal.

is transmitted, it is implied that the UE can estimate the coupling (ie, effective channel) between the transmitted signal and the received signal. Therefore, if no virtualization is performed in the transmission, the received signal

can be expressed as:

를 추정할 수 있다.UE is an effective channel

can be estimated.

In LTE Rel-10, up to 8 CSI-RS ports can be configured, that is, the UE can estimate channels from up to 8 transmit antenna ports. In LTE Release 13, the number of CSI-RS ports that can be configured is extended to a maximum of 16 ports (3GPP TS 36.213, 3GPP TS 36.211). In LTE Release 14, supporting up to 32 CSI-RS ports is under consideration.

The concept of zero-power CSI-RS resources (also known as muted CSI-RS), which is configured like regular CSI-RS resources, relates to CSI-RS, whereby the UE transmits data Notice that the transport is mapped around those resources. The intent of zero-power CSI-RS resources is to enable the network to mute transmission on corresponding resources, perhaps in order to increase the SINR of a corresponding non-zero power CSI-RS transmitted at a neighboring cell/transmission point. will do For LTE Rel-11, a special zero-power CSI-RS was introduced that the UE is directed to use to measure interference + noise. The UE may assume that the transmission points (TPs) of interest are not transmitting on the zero-power CSI-RS resource, and thus the received power may be used as a measure of interference + noise.

Based on the designated CSI-RS resource, and based on the interference measurement configuration (eg, zero-power CSI-RS resource), the UE can estimate the effective channel, and noise + interference, and consequently the specific channel. The rank, precoding matrix, and MCS may be determined to recommend the best match.

Some embodiments of the present disclosure may be used with two-dimensional antenna arrays; Some of the presented embodiments use such antennas. Such antenna arrays can be described (in part) by _{the number N h} of antenna columns corresponding to the horizontal dimension, _{the number N v} of antenna rows corresponding to the vertical dimension, and the number N _{p of dimensions corresponding to different polarizations.} . The total number of antennas is N=N _h N _v N _p . It should be pointed out that the concept of an antenna is non-limiting in the sense that an antenna may refer to any virtualization (eg, linear mapping) of physical antenna elements. For example, pairs of physical sub-elements may be fed the same signal and thus may share the same virtualized antenna port.

An example of a 4x4 array with cross-polarized antenna elements is shown in FIG. 8 .

,

, 및

를 고려하는 것이다. 그러한 2D 코드북들은 수직 또는 수평 차원들을 안테나 포트들이 연관되는 차원들에 엄격하게 관련시키지 않을 수 있다. 그러므로, 2D 코드북들은 안테나 포트들의 제1 및 제2 개수 N₁ 및 N₂를 갖는 것으로 고려될 수 있고, 여기서 N₁은 수평 또는 수직 차원에 대응할 수 있고, 따라서 N₂는 나머지 차원에 대응한다. 즉,

이면

인 한편,

이면

이다. 마찬가지로, 2D 코드북들은 안테나 포트들을 편파에 엄격하게 관련시키지 않을 수 있고, 아래에 설명되는 바와 같이, 2개의 빔 또는 2개의 포트를 결합하기 위해 사용되는 코-페이징 메커니즘들과 함께 설계될 수 있다.Precoding can be interpreted as multiplying the signal with different beamforming weights prior to transmission for each antenna. A typical approach is to fit the precoder to the antenna form factor, i.e. when designing the precoder codebook.

,

, and

will consider Such 2D codebooks may not strictly relate the vertical or horizontal dimensions to the dimensions to which the antenna ports are associated. Therefore, 2D codebooks may be considered to have a first and a second number of antenna ports N ₁ and N _{2 , where N 1} may correspond to a horizontal or vertical dimension, and thus N ₂ corresponds to the remaining dimension. in other words,

back side

On the other hand,

back side

am. Likewise, 2D codebooks may not strictly relate antenna ports to polarization, and may be designed with co-paging mechanisms used to combine two beams or two ports, as described below.

개의 안테나를 갖는 단일 편파 균일 선형 어레이(uniform linear array)(ULA)를 사용하여 단일 계층 전송을 프리코딩하는 데 사용되는 프리코더 벡터는 다음과 같이 정의된다:A common type of precoding is to use a DFT precoder, where

A precoder vector used to precode a single layer transmission using a single polarization uniform linear array (ULA) with n antennas is defined as:

은 프리코더 인덱스이고

은 정수 오버샘플링 인자이다. 편파당

개의 안테나(그리고, 총

개의 안테나)를 갖는 이중 편파 균일 선형 어레이(ULA)를 위한 프리코더는 마찬가지로 다음과 같이 정의될 수 있다:here,

is the precoder index

is an integer oversampling factor. partisan party

antennas (and total

A precoder for a dual polarization uniform linear array (ULA) with two antennas) can be defined as follows:

는 예를 들어 QPSK 알파벳 φ∈{0,π/2,π,3π/2} 중에서 선택될 수 있는 두 개의 편파 사이의 코-페이징 인자이다.here,

is the co-phasing factor between the two polarizations, which can be selected, for example, from the QPSK alphabet φ∈{0,π/2,π,3π/2}.

안테나를 갖는 2차원 균일 평면 어레이(UPA)에 대한 대응하는 프리코더 벡터는 두 개의 프리코더 벡터의 크로네커 곱(Kronecker product)을 취함으로써

로서 생성될 수 있고, 여기서

는

차원의 정수 오버샘플링 인자이다. 각각의 프리코더

는 DFT 빔을 형성하고, 모든 프리코더

는 DFT 빔들의 그리드를 형성한다. 그 예가 도 9에 도시되어 있고, 여기서

및

이다. 이하의 섹션들 전반에서, 'DFT 빔들' 및 'DFT 프리코더들'이라는 용어들은 교환가능하게 사용된다.

The corresponding precoder vector for a two-dimensional uniform planar array (UPA) with antenna is obtained by taking the Kronecker product of the two precoder vectors.

can be created as, where

Is

An integer oversampling factor of the dimension. each precoder

form the DFT beam, and all precoders

form a grid of DFT beams. An example is shown in Fig. 9, where

and

am. Throughout the sections below, the terms 'DFT beams' and 'DFT precoders' are used interchangeably.

을 갖는 빔은 프리코딩 가중치들

이 전송에서 사용될 때 가장 큰 에너지가 전송되는 방향에 의해 식별될 수 있다. 또한, 빔의 사이드로브들(sidelobes)을 낮추기 위해, 크기 테이퍼(magnitude taper)가 DFT 빔들과 함께 사용될 수 있다. 크기 테이퍼링을 갖는 N₁ 및 N₂ 차원들을 따른 1D DFT 프리코더는 다음과 같이 표현될 수 있다:More generally, index pairs

Beams with the precoding weights

When used in this transmission, the greatest energy can be identified by the direction in which it is transmitted. Also, a magnitude taper may be used with DFT beams to lower the sidelobes of the beam. _{A 1D DFT precoder along N 1} and N ₂ dimensions with magnitude tapering can be expressed as:

,

,

은 진폭 스케일링 인자들이다.

는 테이퍼링 없음에 대응한다. DFT 빔들(진폭 테이퍼링이 있거나 없음)은 2개의 차원 각각을 따른 요소들 사이의 선형 위상 시프트를 갖는다. 일반성을 잃지 않고서,

의 요소들은

=

에 따라 정렬되고, 그에 의해 인접한 요소들은 차원

를 따르는 인접한 안테나 요소들에 대응하고,

만큼 이격된

의 요소들은 차원

을 따르는 인접한 안테나 요소들에 대응하는 것으로 가정될 수 있다. 그러면,

의 두 개의 요소

와

사이의 위상 시프트는 다음과 같이 표현될 수 있다:here,

are amplitude scaling factors.

corresponds to no tapering. DFT beams (with or without amplitude tapering) have a linear phase shift between elements along each of two dimensions. without losing generality,

the elements of

=

ordered according to , whereby adjacent elements are dimensioned

corresponding to adjacent antenna elements along

spaced apart

elements of the dimension

may be assumed to correspond to adjacent antenna elements along then,

two elements of

Wow

The phase shift between can be expressed as:

및

(

,

,

, 및

임)은 빔

의 2개의 엔트리를 식별하는 정수들이고, 그에 의해

는 제1 안테나 요소(또는 포트)에 맵핑되는 빔

의 제1 엔트리를 나타내고,

는 제2 안테나 요소(또는 포트)에 맵핑되는 빔

의 제2 엔트리를 나타내게 된다.here,

and

(

,

,

, and

is) is a beam

are integers that identify two entries in

is the beam mapped to the first antenna element (or port)

represents the first entry of

is the beam mapped to the second antenna element (or port)

will indicate the second entry of .

및

는 실수이다. 진폭 테이퍼링이 사용되는 경우,

이고, 그렇지 않으면

이다.

and

is a mistake When amplitude tapering is used,

and otherwise

am.

는 축, 예를 들어 수평 축을 따른 방향에 대응하는 위상 시프트이다('방위각').

is the phase shift corresponding to the direction along an axis, for example the horizontal axis ('azimuth').

는 축, 예를 들어 수직 축을 따른 방향에 대응하는 위상 시프트이다('고도').

is the phase shift corresponding to the direction along an axis, for example the vertical axis ('elevation').

로 형성된 제k 빔

는 대응하는 프리코더

에 의해, 즉

로 또한 지칭될 수 있다. 따라서, 빔

는 복소수들(complex numbers)의 세트로서 기술될 수 있고, 세트의 각각의 요소는, 빔의 요소가 빔의 임의의 다른 요소에 관련되도록 적어도 하나의 복소 위상 시프트에 의해 특징지어지고, 여기서

=

이고,

는 빔

의 제i 요소이고,

은 빔

의 제i 요소와 제n 요소에 대응하는 실수이고; p 및 q는 정수들이고;

및

는 각각 복소 위상 시프트들

및

을 결정하는 인덱스 쌍

을 갖는 빔에 대응하는 실수들이다. 인덱스 쌍

는 빔

가 UPA 또는 ULA에서 전송 또는 수신을 위해 사용될 때 평면파의 출발 또는 도착 방향에 대응한다. 빔

는 단일 인덱스

=

로, 즉 수직 또는

차원을 따라 먼저 식별되거나, 대안적으로는

로, 즉 수평 또는

차원을 따라 먼저 식별될 수 있다. Therefore, the precoder

kth beam formed by

is the corresponding precoder

by, i.e.

may also be referred to as Therefore, the beam

can be described as a set of complex numbers, where each element of the set is characterized by at least one complex phase shift such that the element of the beam is related to any other element of the beam, wherein

=

ego,

silver beam

is the i element of

silver beam

real numbers corresponding to the i-th element and the n-th element of ; p and q are integers;

and

are the complex phase shifts, respectively.

and

index pair that determines

Real numbers corresponding to beams with index pair

silver beam

corresponds to the direction of departure or arrival of a plane wave when used for transmission or reception in UPA or ULA. beam

is a single index

=

by, i.e. vertical or

First identified along a dimension, or alternatively

to, i.e. horizontal or

It can be identified first along a dimension.

Next, extending the precoder to dual-polarized ULA can be done as follows:

는 다음과 같이 DFT 프리코더 벡터들의 열들을 첨부함으로써 생성될 수 있다:Precoder matrix for multi-layer transmission

can be generated by appending columns of DFT precoder vectors as follows:

및

의 특별한 경우에, 다음과 같이 된다:where R is the number of transport layers, that is, the transport rank. rank-2 DFT precoder,

and

In the special case of , it becomes:

값들에 대해

를 통해 검색한다. 랭크=2의 경우, UE는 모든 가능한

값들에 대해

를 통해 검색한다.For each rank, all precoder candidates form a 'precoder codebook' or 'codebook'. The UE may first determine the rank of the estimated downlink wideband channel based on the CSI-RS. After the rank is identified, for each subband, the UE then searches all precoder candidates in the codebook for the determined rank to find the best precoder for the subband. For example, for rank=1, the UE

about the values

search through For rank=2, the UE can

about the values

search through

In the case of multi-user MIMO (MU-MIMO), two or more users within the same cell are co-scheduled for the same time-frequency resource. That is, two or more independent data streams are simultaneously transmitted to different UEs, and the spatial domain is used to separate the respective streams. By transmitting several streams simultaneously, the capacity of the system can be increased. However, this occurs at the cost of reducing the SINR per stream, since power must be shared between the streams and the streams will cause interference with each other.

When increasing the antenna array size, increased beamforming gain will result in higher SINR, but (for large SINRs) user throughput only logarithmically depends on the SINR, so instead, the gains in the SINR are It is advantageous to switch to a multiplexing gain that increases linearly with the number of them.

Accurate CSI is required to perform proper nullforming between co-scheduled users. In the current LTE Rel.13 standard, there is no special CSI mode for MU-MIMO, so the MU-MIMO scheduling and precoder configuration is based on the existing CSI reporting designed for single-user MIMO (i.e., DFT-based precoder). PMI, RI and CQI). The reported precoder contains only information about the strongest channel direction for the user and may not contain enough information to do proper null formation, which leads to a large amount of interference among the co-scheduled users, This can turn out to be quite difficult for MU-MIMO, as it can reduce the benefits of MU-MIMO.

가 사용되는 경우, 빔들은 코-페이징으로 결합되지 않지만, 선택된 빔과 연관된 포트 쌍들은 코-페이징된다. 결과적으로, 이러한 DFT 기반 프리코더들은 '단일 빔' 프리코더들로서 고려될 수 있다. 그러므로, 멀티-빔 프리코더들은 포트 쌍들뿐만 아니라 빔들에 걸쳐 코-페이징이 적용되는 확장이다. 여기에서는 하나의 그러한 코드북이 설명된다. 멀티-빔 코드북은 구체적으로 수평 및 수직 차원에 관련한 코드북의 2차원으로 설명되지만, 코드북은 위에서 설명된 바와 같이 제1 또는 제2 차원이 수평 또는 수직 안테나 포트에 관련되는 일반적인 경우에도 동일하게 적용가능하다.The DFT-based precoders discussed above and used in LTE Rel-13 compute co-phasing across a pair of (typically differently polarized) ports. More than one beam in CSI reporting

When is used, the beams are not co-phased, but port pairs associated with the selected beam are co-phased. Consequently, these DFT based precoders can be considered as 'single beam' precoders. Therefore, multi-beam precoders are extensions where co-phasing is applied across beams as well as port pairs. One such codebook is described herein. The multi-beam codebook is specifically described as two dimensions of the codebook with respect to the horizontal and vertical dimensions, but the codebook is equally applicable to the general case where the first or second dimension is related to the horizontal or vertical antenna port as described above. do.

은 크기 N×N의 DFT 행렬로서 정의되는데, 즉

의 요소들은

로 정의된다.

=

은

에 대해 정의된 크기 N×N의 회전 행렬로 더 정의된다.

에 왼쪽으로부터

을 곱하면, 엔트리들

을 갖는 회전된 DFT 행렬이 생성된다. 회전된 DFT 행렬

=

는 벡터 공간

에 더 걸쳐있는 정규화된 직교 열 벡터들

로 구성된다. 즉, 임의의 q에 대한

의 열들은

의 직교 기저(orthonormal basis)이다.

is defined as a DFT matrix of size N×N, i.e.

the elements of

is defined as

=

silver

It is further defined as a rotation matrix of size N×N defined for

from left to

Multiplying by , the entries

A rotated DFT matrix with Rotated DFT Matrix

=

is a vector space

Normalized orthogonal column vectors further spanning

is composed of That is, for any q

the columns of

is the orthonormal basis of .

In some embodiments, the codebook design is created by extending the (rotated) DFT matrices, which were the appropriate transforms for single polarization ULA as discussed above, to also fit the more general case of double polarization 2D UPA.

=

로서 정의된다.

의 열들

은 벡터 공간

의 직교 기저를 구성한다. 그러한 열

는 이후에 (DFT) 빔으로 표시된다.The rotated 2D DFT matrix is

=

is defined as

columns of

silver vector space

constitute the orthogonal basis of such heat

is later denoted as a (DFT) beam.

A dual polarization beam spatial transform matrix suitable for UPA is generated, where the upper left and lower right elements correspond to two polarizations:

의 열들

는 벡터 공간

의 직교 기저를 구성한다. 이러한 열

는 이하에서 단일 편파 빔(SP-빔)으로 표기되는데, 왜냐하면 그것은 단일 편파에서 전송된 빔

에 의해 구성되기 때문이다(즉,

또는

)]. 또한, 편파들 둘 다에서 전송된 빔을 지칭하기 위해 이중 편파 빔 표기가 도입된다[편파 코-페이징 인자

로 결합됨, 즉

].

columns of

is a vector space

constitute the orthogonal basis of these columns

is denoted hereinafter as a single polarized beam (SP-beam), because it is a beam transmitted at single polarization.

Because it is constituted by (i.e.,

or

)]. Also, a double polarization beam notation is introduced to refer to a beam transmitted in both polarizations [polarization co-phasing factor]

combined with , i.e.

].

의 열 서브셋만을 선택함으로써 채널 에너지의 충분히 많은 부분이 캡쳐되며, 즉, 피드백 오버헤드를 낮게 유지하는 두 개의 SP-빔을 기술하면 충분하다. 그러므로,

의

열들을 구성하는 열 서브셋

을 선택하면, 감소된 빔 공간 변환 행렬

=

이 생성되고, 예를 들어, 열 번호

를 선택하면, 감소된 빔 공간 변환 행렬

이 생성된다.Using the assumption that the channel is rather sparse,

A sufficiently large fraction of the channel energy is captured by selecting only a thermal subset of so,

of

Column subsets that make up the columns

If is selected, the reduced beam space transformation matrix

=

This is created, for example, the column number

If is selected, the reduced beam space transformation matrix

this is created

The most common precoder structures for single layer precoding are:

는 복소 빔 코-페이징 계수들이다.here

are the complex beam co-phasing coefficients.

는 제k 빔

을 코-페이징 계수

로 코-페이징함으로써 구성된 빔들의 선형 조합으로 기술될 수 있다. 이러한 빔 코-페이징 계수는

에 따라 다른 빔들에 대해 적어도 빔의 위상을 조절하는 스칼라 복소수이다. 빔 코-페이징 계수가 상대 위상만 조절하는 경우, 그것은 단위 크기 복소수이다. 일반적으로, 빔의 상대 이득을 또한 조절하는 것이 바람직하며, 이 경우 빔 코-페이징 계수는 단위 크기가 아니다.In the above equation, the precoder

is the kth beam

is the co-phasing coefficient

It can be described as a linear combination of beams constructed by lo co-phasing. These beam co-phasing coefficients are

It is a complex scalar number that adjusts at least the phase of a beam with respect to other beams according to . If the beam co-phasing coefficient only adjusts the relative phase, it is a unit-scale complex number. In general, it is desirable to also adjust the relative gain of the beam, in which case the beam co-phasing coefficient is not unit-sized.

A more refined multi-beam precoder structure is achieved by separating the complex coefficients in the power (or amplitude) and phase parts as follows:

를 복소 상수

와 곱하는 것은 그것의 빔포밍 속성들을 변경시키지 않으므로(다른 단일 편파 빔들에 대한 위상 및 진폭만이 중요하기 때문임), 일반성을 잃지 않고서, 예를 들어 SP-빔 1에 대응하는 계수들은

로 고정되고,

라고 가정할 수 있고, 그에 의해 하나 적은 빔에 대한 파라미터들은 UE로부터 기지국으로 시그널링될 필요가 있게 된다. 또한, 프리코더는 예를 들어, 합계 전력 제한이 충족되도록, 즉

이 되도록 정규화 인자와 승산되는 것으로 더 가정될 수 있다. 이러한 정규화 인자는 명확성을 위해 본 명세서의 수학식들에서 생략된다.Precoder Vector

is a complex constant

Since multiplying with does not change its beamforming properties (since only the phase and amplitude for other single polarized beams matter), without loss of generality, for example the coefficients corresponding to SP-beam 1 are

is fixed with

, whereby parameters for one less beam need to be signaled from the UE to the base station. Also, the precoder can, for example, ensure that the sum power limit is met, i.e.

It can be further assumed that it is multiplied with a normalization factor so that This normalization factor is omitted from the equations herein for clarity.

의 가능한 열 선택은, 열

이 선택되면 열

도 선택되도록 제한된다. 즉, 제1 편파에 맵핑된 특정 빔에 대응하는 SP-빔이 선택되면, 예를 들어

이면, 이것은 SP-빔

도 선택됨을 암시한다. 즉, 제2 편파에 맵핑된 상기 특정 빔에 대응하는 SP-빔도 선택된다. 이것은 피드백 오버헤드를 감소시킬 것인데, 왜냐하면

의

열만이 선택되고 기지국으로 다시 시그널링되어야 하기 때문이다. 즉, 열 선택은 SP-빔 레벨이 아니라 빔(또는 DP 빔) 레벨에서 행해진다. 특정 빔이 편파들 중 하나에서 강한 경우, 이는 전형적으로 그 빔이 적어도 광대역 의미에서 다른 편파에서도 강할 것이고, 따라서 이러한 방식으로 열 선택을 제한하는 것의 손실이 성능을 크게 감소시키지 않을 것임을 암시한다. 이하의 논의에서, (달리 언급되지 않는 한) DP 빔들의 사용이 일반적으로 가정된다.In some cases,

The possible column choices of

If is selected, open

is also limited to be selected. That is, if the SP-beam corresponding to the specific beam mapped to the first polarization is selected, for example,

, this is the SP-beam

also implies that it is selected. That is, the SP-beam corresponding to the specific beam mapped to the second polarization is also selected. This will reduce the feedback overhead, because

of

This is because only the column has to be selected and signaled back to the base station. That is, column selection is done at the beam (or DP beam) level, not at the SP-beam level. If a particular beam is strong in one of the polarizations, this typically implies that that beam will be strong in the other polarization, at least in the broadband sense, and thus the loss of limiting thermal selection in this way will not significantly reduce performance. In the discussion below, the use of DP beams (unless stated otherwise) is generally assumed.

의 선택) 및 상대 SP-빔 전력/진폭들(즉, 행렬

의 선택)은 특정 주파수 입도로 선택되는 한편, SP-빔 위상(즉, 행렬

의 선택)은 다른 특정 주파수 입도로 선택된다. 하나의 그러한 경우에서, 특정 주파수 입도는 광대역 선택(즉, 전체 대역폭에 대한 하나의 선택)에 대응하는 한편, 상기 다른 특정 주파수 입도는 부대역 별 선택에 대응한다(즉, 캐리어 대역폭은 전형적으로 1-10 PRB로 구성되는 다수의 부대역으로 분할되고, 각각의 부대역에 대해 별도의 선택이 행해진다).In some cases, the multi-beam precoder is factored into two or more factors selected with different frequency-granularity to reduce feedback overhead. In such cases, SP-beam selection (i.e., matrix

) and relative SP-beam power/amplitudes (i.e. matrix

) is chosen at a specific frequency granularity, while the SP-beam phase (i.e., matrix

) is chosen as another specific frequency granularity. In one such case, a specific frequency granularity corresponds to a wideband selection (ie one selection for the entire bandwidth), while the other specific frequency granularity corresponds to a subband-specific selection (ie the carrier bandwidth is typically 1 -10 is divided into multiple subbands consisting of PRBs, and a separate selection is made for each subband).

로 인수분해되며, 여기서

은 특정 주파수 입도로 선택되고

는 다른 특정 주파수 입도로 선택된다. 그러면 프리코더 벡터는

로서 표현될 수 있다. 이 표기법을 사용하여, 상기 특정 주파수 입도가

의 광대역 선택에 대응하고, 상기 다른 특정 주파수 입도가

의 부대역 별 선택에 대응하면, 부대역

에 대한 프리코더 벡터는

로 표현될 수 있다. 즉,

만이 부대역 인덱스

의 함수이다.In a typical case, the multi-beam precoder vector is

is factored into , where

is chosen with a specific frequency granularity and

is chosen with another specific frequency granularity. Then the precoder vector is

can be expressed as Using this notation, the specific frequency granularity is

Corresponding to the broadband selection of, the other specific frequency granularity is

In response to the subband selection of

The precoder vector for is

can be expressed as in other words,

only subband index

is a function of

Thus, what needs to be fed back to the eNodeB by the UE is:

의 선택된 열들, 즉

단일 편파 빔들. 이는 최대

비트들을 필요로 한다.

selected columns of , i.e.

single polarized beams. This is the maximum

bits are required.

및

. 예를 들어, Q의 소정 값에 대해

. 그러면, 대응하는 오버헤드는

비트들일 것이다.Vertical and horizontal DFT basis rotation factors

and

. For example, for a given value of Q

. Then, the corresponding overhead is

will be bits

.

이 가능한 이산 전력 레벨들의 수인 경우, SP-빔 전력 레벨들을 피드백하기 위해

이 필요하다.(Relative) power levels of SP-beams

.

to feed back the SP-beam power levels, if is the number of possible discrete power levels.

I need this.

. 예를 들어, K의 소정 값에 대해,

=

,

이다. 대응하는 오버헤드는

리포트 당 랭크 당

비트일 것이다.Co-phasing factors of SP-beams

. For example, for a given value of K,

=

,

am. The corresponding overhead is

per rank per report

it will be a bit

에 대해 '빔 결합 계수'라는 용어가 사용되지만, 코-페이징 인자들은 상이한 빔들뿐만 아니라 상이한 편파들을 가진 요소들을 결합할 수 있음에 유의한다.Recently, 3GPP agreed on the following tentative assumptions used to develop physical layer specifications of Rel-14 advanced CSI based on multi-beam precoders. Here, the co-phasing factors

Although the term 'beam coupling coefficient' is used for , it is noted that co-phasing factors can combine elements with different polarizations as well as different beams.

The precoders should be normalized in the following equation.

●

및

- About Rank 1:

and

및

- About Rank 2:

and

-

●

는 빔 수이다.●

is the number of beams.

는 오버샘플링된 그리드로부터의 2D DFT 빔이다.●

is the 2D DFT beam from the oversampled grid.

-

-

빔

에 대한 빔 전력 스케일링 인자●

beam

Beam power scaling factor for

편파

및 계층

상에서의 빔

에 대한 빔 결합 계수 ●

partiality

and layer

beam on

Beam coupling coefficient for

및

의 표시들은 (적어도 일부 경우들에서) PUCCH 포맷 2에서 지원될 수 있는 것보다 더 크기 때문에, PUCCH 포맷 2의 보고가 구성될 때,

및/또는

에 대한 피드백이 수정되어야 한다.Feedback on PUSCH is supported and feedback on PUCCH is supported. Feedback on PUCCH should be supported,

and

Since the indications of (at least in some cases) are larger than can be supported in PUCCH format 2, when reporting of PUCCH format 2 is configured,

and/or

feedback should be corrected.

10A-13A illustrate procedures for reporting CSI feedback on a physical channel in accordance with some embodiments of the present disclosure.

10A shows a procedure in which the second node 14 reports CSI feedback to the first node 12 with a small payload on a physical channel (step 100A). In this specification, CSI feedback according to some embodiments is referred to as rich CSI feedback. As used herein, rich CSI refers to CSI that conveys more information than traditional CSI. For example, the rich CSI may be CSI for LTE Advanced or NR Type 2. Additional examples and explanations are included below. According to some embodiments, reporting of CSI feedback has a small payload. Also, as used herein, a small payload is a payload that contains fewer total bits than would normally have to be transmitted in other applications. For example, an application for advanced CSI is to transmit a subband PMI using multiple bits per subband (which is considered significant). In comparison to this application, according to some disclosed embodiments, when transmitting a wideband PMI and the PMI needs to be further subsampled to fit the feedback channel, the payload is limited. In such a case, the small payload is the payload so that it is small enough or smaller to fit the feedback channel. This can be accomplished in a number of different ways, some of which are discussed below. Specifically, as shown in FIG. 11A , the second node 14 identifies a subset of codebook entries from the advanced CSI codebook of coefficients (step 200A). Next, the second node 14 selects a codebook entry from the subset (202A). The index of the selected codebook entry is reported to the first node 12 (step 204A). In this way, the constraints of a small payload physical channel are met even when transmitting rich CSI.

12A shows a procedure in which the second node 14 reports a rank indicator and a beam count indicator in a first transmission (step 300A) and reports a co-paging indicator in a second transmission (step 302A). do. In some embodiments, both of these transmissions are transmitted on the same uplink control channel. In some embodiments, these transmissions are transmitted on a channel acting as a control channel. In some embodiments, the second node 14 determines the number of beams L used to construct the multi-beam CSI report (step 304A). Next, the second node 14 determines a beam indicator for the first beam, the beam indicator identifies the index of the beam in the multi-beam CSI report if L is at least l, otherwise L is less than l identify it (step 306A).

13A shows that the second node 14 reports the CSI corresponding to the first number of beams when the CSI corresponds to the first rank (step 400A) and the second when the CSI corresponds to the second rank. A procedure for reporting the CSI corresponding to the number of beams is shown (step 402A).

10B to 13B are diagrams illustrating similar operations on the receiving side such as the first node 12 .

LTE Rel-13 Class A codebook-based periodic CSI feedback is carried in PUCCH format 2 over at least three transmissions, ie:

● 1st transmission: RI

● Second transmission: W ₁

● 3rd transmission: W ₂ and CQI

For each transmission, up to 11 bits can be transmitted. The main goal is to have three transmissions even for advanced CSI feedback through PUCCH format 2.

Since the periodic CSI feedback can be multiplexed over several PUCCH transmissions, the individual components including the PMI feedback indicating the selection of _{W 1} and W _{2 are repeated.}

The report of W ₁ may be split into separate components as described in more detail in the background.

안테나 포트인 최악의 경우에서,

= 4 비트● Leading beam selection:

In the worst case, the antenna port,

= 4 bits

=4 비트● Beam rotations:

=4 bits

=3 비트● Second beam selection:

=3 bits

● Beam relative power: 2 bits

_{Although the codebook defines a precoder as linear combinations of L=2 beams (or N DP} beams using the notation in the description of multi-beam precoders above), by setting the relative beam power of the second beam to zero, L It is possible to result in an effective precoder containing only =1 beams. In such a case, the precoder components describing the second beam do not need to be known to configure the precoder, and thus signaling indicative of the precoder components is not necessary.

비트를 사용하는데, 여기서 L은 빔의 수이고, N_p는 W₂의 요소 당 위상 비트의 수이고(또는 위에서 논의된 멀티-빔 프리코더의 표기법을 사용하면

비트), r은 랭크이다. QPSK 성상도가 사용되므로, N_p = 2이고, L=1 및 L=2에 대한 부대역 당 W₂를 위한 비트 수는 표 2에 요약된다.Therefore, the reporting of the _{W 2 matrix is per subband}

bits, where L is the number of beams, N _p is the number of phase bits per element of W ₂ (or using the notation of the multi-beam precoder discussed above,

bit), r is the rank. Since the QPSK constellation is used, N _{p = 2, and the number of bits for W 2} per subband for L = 1 and L = 2 is summarized in Table 2.

For PUCCH format 2, the total payload cannot be greater than 11 bits, as it may be beneficial to report _{W 2} along with the CQI in the PUCCH transmission. Since CQI occupies 4 and 7 bits for 1 and 2 codewords, respectively, W ₂ cannot occupy more than 7 or 4 bits for rank 1 or 2 (in LTE, rank 1 uses 1 codeword, while Because rank 2 uses 2 codewords). Thus, the wideband W ₂ PMI for rank 1 can fit PUCCH format 2 without subsampling, whereas for L=2, it is necessary to subsample 12 bits to 4 bits for rank 2 for L=2. This constitutes the actual subsampling.

Given the above constraints, three different payload sizes (2, 4 or 6) may be used for _{W 2 in PUCCH format 2 .} When the payload size changes, the eNB must know the number of ranks and beams used to calculate _{W 2 .} In Rel-13, since the eNB determines the size of the CQI field based on the RI, the principle can be reused to determine the rank used to calculate _{W 2 .} If the beam power fields are encoded independently of the W _2, the beam can be used to determine the W ₂ may be determined by the eNB also from the reported beam power field.

The table below shows the W ₂ payload size.

_{The rich W 2} CSI feedback of LTE Rel-14 implements scalar quantization and polarization co-phasing of the beam for each layer, where the W ₂ matrix for rank 2 can be expressed as:

, 즉 각각의 요소는 QPSK 성상도로부터 독립적으로 선택될 수 있다. 더 명확히 하기 위해,

는 제1 편파 상의 제1 및 제2 빔의 상대 위상을 나타내고,

는 제1 빔의 두 편파 사이의 상대 위상을 나타내고,

는 제1 편파 상의 제1 빔과 제2 편파 상의 제2 빔의 상대 위상을 나타낸다. 스칼라 양자화가 사용되므로, W₂는 D = 6차원 벡터

를 사용하여 파라미터화될 수 있고, 따라서 6 자유도를 가져서, 12 비트로 표현되는

=4096개의 가능한 상태를 야기하는 것으로 고려될 수 있다. 따라서, W₂ 코드북은 k = 0,1,…, S-1로 인덱스화될 수 있다.Here, each

That is, each element may be independently selected from the QPSK constellation. For more clarity,

represents the relative phase of the first and second beams on the first polarization,

denotes the relative phase between the two polarizations of the first beam,

denotes the relative phase of the first beam on the first polarization and the second beam on the second polarization. Since scalar quantization is used, W ₂ is D = 6D vector

can be parameterized using

=4096 possible states can be considered. Therefore, the W ₂ codebook is k = 0,1,… , may be indexed as S-1.

를 보고하는 것이며, 여기서

이다. 그러나, 이러한 서브샘플링은 코드북의 구조를 이용하지 않으며, 낮은 CSI 입도를 제공할 수 있다.One approach to subsampling the W ₂ codebook is simply to subsample the index k such that only every xth index can be selected, and instead

to report, where

am. However, such subsampling does not use the structure of the codebook and may provide low CSI granularity.

및 이진 위상 시프트 키잉(BPSK) 성상도가 사용되게 하는 것이다. 그러나, 이 예에서는, 여전히 랭크 2에 대한 4 비트의 목표를 초과하는 6 비트의 피드백 오버헤드를 필요로 한다. BPSK 성상도 포인트들은 QPSK 성상도에 포함되기 때문에, 서브샘플링된 코드북 내의 모든 결과적인 프리코더들이 서브샘플링되지 않은 코드북에 포함되므로, 성상도 알파벳 크기를 이러한 방식으로 낮추는 것은 코드북 서브샘플링을 구성한다는 점에 유의한다.Another approach to subsampling the codebook is to lower the constellation alphabet size, e.g.

and a binary phase shift keying (BPSK) constellation to be used. However, in this example, it still requires a feedback overhead of 6 bits, which exceeds the target of 4 bits for rank 2. Since the BPSK constellation points are included in the QPSK constellation, all the resulting precoders in the subsampled codebook are included in the non-subsampled codebook, so lowering the constellation alphabet size in this way constitutes codebook subsampling. take note of

, 및

로부터 프리코더 행렬로의 고정 맵핑으로부터 생성될 수 있다.However, to further reduce the feedback overhead, _{a method of rich CSI W 2} codebook subsampling is presented here. This method works by parameterizing the W2 codebook with a parameter number M that is less than the D parameters required over the entire codebook. That is, the subsampled _{precoders of W 2} are size-M vectors

, and

can be generated from a fixed mapping from to the precoder matrix.

이도록 M = 1을 고려한다. 그러면, 서브샘플링된 프리코더 코드북은 예를 들어 다음과 같이 생성될 수 있다.As an exemplary embodiment,

Consider M = 1 so that Then, the subsampled precoder codebook may be generated as follows, for example.

인 경우, 서브샘플링된 코드북에 4¹ = 4개의 가능한 W₂ 행렬이 그에 따라 존재한다. 모든 가능한

는 서브샘플링되지 않은 코드북에 포함되므로,

는 새로운 별도의 코드북이 아니라 코드북 서브샘플링을 구성함에 유의한다. 이것이 참이 되려면, 서브샘플링된 코드북 내의 프리코더 행렬들의 각각의 요소

는 서브샘플링되지 않은 코드북과 동일한 성상도에 속할 것이 요구된다[예를 들어, QPSK {1, j, -1,- j}]. 위상 시프트 키잉(PSK) 성상도는 곱셈에 대해 닫혀있으므로, 임의의 수의 PSK 심볼들을 곱함으로써

를 구성할 수 있다. 따라서,

내의 요소들은 서브샘플링되지 않은 코드북의 요소들과 동일한 성상도로부터 온 것이고,

내의 요소들은

또는 다른 PSK 심볼들의 요소들을 곱함으로써 형성된 경우("-1"는 PSK 심볼에 속한다는 점에 유의해야 함),

는 서브샘플링되지 않은 코드북에 포함되도록 보장된다. 본 방법에 따라 코드북 서브샘플링들을 생성하기 위한 이러한 규칙들에 기초하여, 성능과 피드백 오버헤드 사이의 양호한 트레이드오프를 제공하는

행렬이 설계될 수 있다.

, there are accordingly 4 ¹ = 4 possible W ₂ matrices in the subsampled codebook. all possible

is included in the unsubsampled codebook,

Note that ? constitutes a codebook subsampling, not a new separate codebook. For this to be true, each element of the precoder matrices in the subsampled codebook is

is required to belong to the same constellation as the non-subsampled codebook [eg, QPSK {1, j, -1,- j}]. Since the phase shift keying (PSK) constellation is closed to multiplication, by multiplying any number of PSK symbols

can be configured. therefore,

elements in the unsubsampled codebook are from the same constellation,

elements within

or formed by multiplying elements of other PSK symbols (note that "-1" belongs to PSK symbol),

is guaranteed to be included in the non-subsampled codebook. Based on these rules for generating codebook subsamplings in accordance with the present method, it provides a good tradeoff between performance and feedback overhead.

A matrix can be designed.

In some embodiments, the codebook subsampling is generated using two properties:

• The phase offset between the beams is (in part) due to the difference in propagation delay and thus can be similar in both polarizations.

• Precodings on different layers are often chosen to be orthogonal to each other.

및

와 유사할 수 있음을 시사한다. 이는 단일 계층의 프리코딩이 다음과 같이 표현될 수 있도록 서브샘플링 설계에서 사용될 수 있다:The first attribute is the ratios at specific propagation conditions.

and

suggest that it may be similar to This can be used in the subsampling design so that the precoding of a single layer can be expressed as:

는 편파 코-페이징 계수이며, 이들 둘 다는 QPSK 심볼이다. 따라서, 이 설계에서, 비율

은 요구되는 제1 속성을 충족시킨다.where c is the beam co-phasing coefficient,

is the polarization co-phasing coefficient, both of which are QPSK symbols. Therefore, in this design, the ratio

satisfies the required first attribute.

이도록, 제2 계층은 제1 계층에 직교하도록 설계될 수 있으며, 여기서

는 항등 행렬(모두 1을 포함하는 대각선을 제외하고 모두 0인 행렬)이고,

는 음이 아닌 스칼라이다. 이것은 다음과 같이 제1 계층에 대한 계수들은 복사하고 제2 편파에 대응하는 엔트리들을 무시함으로써 달성될 수 있다:to satisfy the second attribute,

so that the second layer may be designed to be orthogonal to the first layer, where

is an identity matrix (matrix all zeros except diagonals containing all ones),

is a nonnegative scalar. This can be achieved by copying the coefficients for the first layer and ignoring the entries corresponding to the second polarization as follows:

=

로부터, 즉 2개의 파라미터를 사용하여 생성되며, 여기서

의 각각의 요소는 QPSK 성상도에 속한다. 따라서, 서브샘플링된 코드북 내의 요소를 나타내기 위해 2 + 2 = 4 비트가 필요하며, 이는 W₂에 대한 PUCCH 피드백 오버헤드에 관한 요건을 충족시킨다.Thus, with this subsampling design, both of the required properties are met. In addition, the subsampled codebook is

=

is generated from, i.e. using two parameters, where

Each element belongs to the QPSK constellation. Therefore, 2 + 2 = 4 bits are needed to indicate an element in the subsampled codebook, which satisfies the requirement regarding PUCCH feedback overhead for _{W 2 .}

In some embodiments, the property that the layers are often chosen to be orthogonal to each other is not used in the subsampling design because it places unnecessary constraints on the channel quantization for some propagation conditions. Instead, each layer is encoded independently. However, the first property mentioned previously is still used, whereby separate beam co-phasing coefficients and polarization coefficients are used, resulting in the following matrix design:

로부터 생성될 수 있다. 그러나, 4 비트 W₂ 리포트의 요건들을 충족시키기 위해, QPSK 성상도로부터 각각의 파라미터가 선택될 수 없는데, 왜냐하면 이것은 8 비트 리포트를 요구하기 때문이다. 그러나, BPSK 성상도 포인트들이 QPSK 성상도 내에 포함되기 때문에, 파라미터들에 대해 더 낮은 차수의 성상도를 사용하는 것은 여전히

가 서브샘플링된 코드북을 구성할 것을 보장할 것이다. 따라서, 각각의 파라미터가 BPSK 성상도로부터 선택되면, 서브샘플링된 코드북은 4 비트로 보고될 수 있고 요건이 충족된다.Thus, the subsampled codebook in this embodiment has four parameters

can be generated from However, to meet the requirements of a 4-bit W ₂ report, each parameter cannot be selected from the QPSK constellation, since this requires an 8-bit report. However, since the BPSK constellation points are included in the QPSK constellation, using a lower order constellation for the parameters is still

will ensure to construct the subsampled codebook. Thus, if each parameter is selected from the BPSK constellation, the subsampled codebook can be reported with 4 bits and the requirement is met.

For the UE _{to report W 2} , it is assumed that L=2 is used when rank=1 and L=1 is used when rank=2. In this case, _{as discussed above with respect to the W 2} payload alternatives, 6 bits and 4 bits may be carried along with the CQI for rank 1 and 2 respectively, thus requiring rank=1 or rank=2 W ₂ . There is no subsampling. For rank=1, _{the full resolution of W 2} is preserved, and the full size W ₂ (6 bits for Rel-14 codebook) is reported. Rank = about 2, a single beam is used for the W _2, which multi-non-sub-sampled - corresponding to W ₂ with a beam codebook, and thus the 4-bit to signal the W ₂ using the Rel-14 codebook in need.

For PUCCH format 2, the following design goals for consistency with Rel-13 operation are identified:

1. All CSI report types must fit 11 bits.

2. Up to three transmissions are required to report RI, CQI, PMI and CRI.

a. RI is carried in one transmission.

b. A wideband CQI of 4 or 7 bits can be used for 1 or 2 codeword transmissions, respectively, and is carried in other PUCCH transmissions.

c. At least the beam index is carried in the third PUCCH transmission.

3. Each transmission shall be as useful as possible to the eNodeB in the absence of other transmissions.

Since the RI often needs to be decoded to determine the size of other CSI fields such as CQI and PMI, it is important that it is reliably received. Consequently, the RI should be multiplexed in the PUCCH transmission with as few other fields as possible, while still providing the necessary CSI. Transmitting as little additional information as possible means that there are fewer bits in the PUCCH carrying the RI, and thus more reliably received at a given received SINR.

The beam power indication and the second beam index require 2 and 3 bits, respectively. On the other hand, the first beam index requires at least 4 bits (8 bits when the index includes rotation as done in the Rel-14 codebook convention). Since the first beam index should be reported together with (or directly included) the beam rotation, these 8 bits should be reported in one PUCCH transmission. Then, overall, the beam power indication and the second beam index are good candidates for multiplexing with the RI, whereas the first beam index and/or the beam rotation are not.

When the RI is multiplexed with the second beam index, if the Rel-13 PUCCH reporting timing is used, the RI (eg, PUCCH reporting type 3 or 7) is likely to be reported slower than the wideband PMI (ie, PUCCH reporting type 2a) Therefore, the two beams will be reported at different rates, which is undesirable because they have the same basic properties and change with propagation at the same rate in time. This unequal reporting rate also has the potential to degrade performance. Therefore, it seems undesirable to report the second beam index along with the RI.

Since the number of beams in a channel, like the rank, identifies the number of parameters needed to approximate the channel, it makes intuitive sense to report the beam power indication as RI, since the number of beams is similar to its rank. The beam power indication also identifies whether the precoder parameters for the second beam need to be known, and thus can be considered a beam count indicator.

또는

)을 나타내는 경우, CSI 리포트는 2개의 빔에 대응한다. 이 경우, 제2 빔 인덱스가 보고되고, PUCCH 상에서 보고되는 광대역 코-페이징 표시자 W₂의 크기는 4 비트일 것이다(위에서 논의된 W₂ 서브샘플링으로). 빔 전력 필드가 제로 값을 나타내면, 제2 빔 인덱스는 보고되지 않으며, RI에 의해 각각 랭크 1 또는 랭크 2가 표시되는지에 따라, PUCCH 상에서 보고되는 광대역 코-페이징 표시자 W₂의 크기는 (또한, 부대역 당 W₂ 빔 코-페이징 오버헤드와 관련하여 위에서 논의된 바와 같이) 2 또는 4 비트일 것이다.The beam power field (also 'beam count indicator') _{may be used to identify the size of the W 2} co-phasing indicator, and the presence of information identifying the second beam. The beam power field corresponding to the second beam is a non-zero value (eg, 1,

or

), the CSI report corresponds to two beams. In this case, the second beam index is reported, and _{the size of the wideband co-paging indicator W 2} reported on PUCCH will be 4 bits (with W ₂ subsampling discussed above). If the beam power field indicates a zero value, the second beam index is not reported, and depending on whether rank 1 or rank 2 is indicated by the RI, respectively, the size of _{the wideband co-paging indicator W 2 reported on the PUCCH is (also , as discussed above with respect to W 2} beam co-paging overhead per subband) will be 2 or 4 bits.

Thus, in an embodiment, both the rank indicator and the beam count indicator are sent in one transmission. The rank indicator identifies the rank used when calculating CSI feedback to which the rank is associated. The beam count indicator may at least identify the number of beams used when calculating the CSI feedback, and may further indicate the relative power of the identified beams in the CSI feedback. The rank and beam count indicators may identify the size of a CSI feedback field transmitted in a separate transmission, such as a _{co-paging indicator (W 2} ) or a beam index (W _{1 ).} In this embodiment, the advanced CSI feedback may be carried on PUCCH format 2 over at least three transmissions, ie:

● 1. First transmission: RI + beam power (or beam count indicator)

● 2. Second transmission: W ₁ (first beam index + beam rotation + second beam index)

● 3rd transmission: W ₂ and CQI

Note that transmissions may be chronologically arranged in their numerical order, although this is not required. Also, they may be transmitted as completely separate transmissions, or as separate parts of the same transmission.

In a related embodiment, a later transmission carries a CQI field and a co-paging indicator field (W ₂ ). The size of the co-paging indicator field is determined at least by the beam count indicator transmitted in the previous transmission, and the size of the CQI field is determined by at least the RI transmitted in the previous transmission.

It may also be desirable to provide an alternative indication of the number of beams used in a multi-beam CSI report. This may allow the number of beams to be reported to the eNB more frequently than when the number of beams is only provided in a report containing the RI, since the RI is generally reported infrequently. In this case, the CSI report for the second (weaker) beam identifies the number of beams and the index of the second beam together. The specific codebook design used in 3GPP fits well here as well, since the second beam index has 7 possible values, so the 8th value indicating the presence or absence of the second beam can fit the 3-bit indicator.

Thus, in an embodiment, the first transmission carries a beam index that is jointly encoded with an indication of whether the second beam is not present, wherein when the second beam is not present corresponds to a beam power of 0 for the second beam. do. Additionally, the second transmission may carry a co-paging indicator field. The size of the co-phasing indicator field is determined by at least an indication that a second beam is not present.

14 and 15 show an exemplary embodiment of a second node 14 , such as a wireless device 14 , in accordance with some embodiments of the present disclosure. 14 is a schematic block diagram of a wireless device 14 (eg, UE 14) in accordance with some embodiments of the present disclosure. As shown, the wireless device 14 includes one or more processors 20 (eg, central processing units (CPUs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and/or the like). and a circuit 18 including a memory 22 . The wireless device 14 also includes one or more transceivers 24 , each including one or more transmitters 26 and one or more receivers 28 coupled to one or more antennas 30 . In some embodiments, the functionality of wireless device 14 described above may be fully or partially implemented, for example, in software stored in memory 22 and executed by processor(s) 20 .

In some embodiments, a computer comprising instructions that, when executed by at least one processor, cause the at least one processor to perform a function of the wireless device 14 in accordance with any of the embodiments described herein. program is provided. In some embodiments, a carrier comprising the above-mentioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer-readable storage medium (eg, a non-transitory computer-readable medium such as a memory).

15 is a schematic block diagram of a wireless device 14 in accordance with some other embodiments of the present disclosure. The wireless device 14 includes one or more modules 32, each of which is implemented in software. The module(s) 32 provide the functionality of the wireless device 14 (eg, the UE 14 ) described herein.

16-18 show exemplary embodiments of a radio network node in accordance with some embodiments of the present disclosure. 16 is a schematic block diagram of a node 12 in accordance with some embodiments of the present disclosure. Other types of network nodes may have similar architectures (particularly with respect to including processor(s), memory, and network interfaces). As shown, the radio access node 12 controls including circuitry including one or more processors 36 (eg, CPUs, ASICs, FPGAs, and/or the like) and memory 38 . system 34 . The control system 34 also includes a network interface 40 . The radio access node 12 also includes one or more radio units 42 each including one or more transmitters 44 and one or more receivers 46 coupled to one or more antennas 48 . In some embodiments, the functionality of radio access node 12 described above may be fully or partially implemented, for example, in software stored in memory 38 and executed by processor(s) 36 . .

17 is a schematic block diagram illustrating a virtualized embodiment of a radio access node 12 in accordance with some embodiments of the present disclosure. Other types of network nodes may have similar architectures (particularly with regard to including processor(s), memory, and network interfaces).

As used herein, a “virtualized” radio access node 12 is a radio access node 12, wherein at least some of the functionality of the radio access node 12 is [e.g., physical processing of the network(s)). is implemented as a virtual component] through a virtual machine(s) running on the node(s). As shown, the radio access node 12 optionally includes a control system 34 as described in connection with FIG. 16 . The radio access node 12 also includes one or more radio units 42 each including one or more transmitters 44 and one or more receivers 46 coupled to one or more antennas 48 as described above. The control system 34 (if present) is connected to the radio unit(s) 42 via, for example, an optical cable or the like. Control system 34 (if present) is connected via network interface 40 to one or more processing nodes 50 connected or included as part of network(s) 52 . Alternatively, if the control system 34 is not present, the one or more radio units 42 are connected to the one or more processing nodes 50 via network interface(s). Each processing node 50 includes one or more processors 54 (eg, CPUs, ASICs, FPGAs, and/or the like), memory 56 , and network interfaces 58 .

In this example, functions 60 of radio access node 12 described herein are implemented in one or more processing node 50 or control system 34 (if present) and one or more processing node 50 . distributed in any desired manner throughout. In some specific embodiments, some or all functionality 60 of radio access node 12 described herein is implemented in one or more virtual environment(s) hosted by processing node(s) 50 . It is implemented as virtual components executed by the machine. As will be appreciated by those skilled in the art, to perform at least some of the required functions, the processing node(s) 50 and the control system 34 (if present) or alternatively a wireless unit Additional signaling or communication between (s) 42 is used. In particular, in some embodiments, the control system 34 may not be included, in which case the wireless unit(s) 42 communicates directly with the processing node(s) 50 via an appropriate network interface(s). do.

In some embodiments, when executed by at least one processor, causes the at least one processor to perform the functions of radio access node 12 or processing node 50 according to any of the embodiments described herein. A computer program is provided that includes instructions to make it happen. In some embodiments, a carrier comprising the computer program product described above is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer-readable storage medium (eg, a non-transitory computer-readable medium such as a memory).

18 is a schematic block diagram of a radio access node 12 in accordance with some other embodiments of the present disclosure. The radio access node 12 includes one or more modules 62, each of which is implemented in software. The module(s) 62 provide the functionality of the radio access node 12 described herein.

Exemplary embodiments

Without being so limited, some illustrative embodiments of the present disclosure are provided below.

1. A method of operating a second node (14) connected to a first node (12, 50) in a wireless communication network, the method comprising:

Reporting (100A) rich CSI feedback to the first node (12, 50) on a physical channel with a small payload

A method of operation comprising a.

2. The method of embodiment 1, wherein the reporting of rich CSI feedback comprises:

identifying a subset of codebook entries from the codebook of coefficients (200A);

selecting a codebook entry from the subset (202A), and

Reporting the index of the selected codebook entry (204A)

comprising, a method of operation.

3. The method of Example 2, comprising:

Each entry in the codebook is identified by an index k;

를 포함하고, L' 및 r은 양의 정수이고;An entry in the codebook with index k is a vector or matrix of complex numbers with L' rows and r columns.

wherein L' and r are positive integers;

each (L′-1)r element of each entry contains a scalar complex number that can be one of the N complex numbers;

이고,

는 상이한 코드북 엔트리들의 인덱스들이고,

는 행렬 또는 벡터 C의 프로베니우스 놈이고;

ego,

are indices of different codebook entries,

is the Frobenius norm of a matrix or vector C;

개의 엔트리를 포함하고; the code book

contains entries;

개의 엔트리 중 하나를 포함하고,

및

은 양의 정수이며, 서브셋 내의 각각의 엔트리는 인덱스에 의해 식별되는, 동작 방법.subset is

contains one of the entries,

and

is a positive integer, and each entry in the subset is identified by an index.

에 대해

인, 동작 방법.4. The method of embodiment 3, wherein the selected codebook entry for the case r=2 may be constructed from M=2 distinct variables, each variable may be one of K=N complex numbers, within a subset each entry

About

In, how it works.

5. The method of embodiment 2, comprising:

Each entry in the codebook contains a vector or matrix;

one or more elements of each entry include a scalar complex number;

and a norm between a matrix or vector difference between any two different codebook entries is greater than zero.

개의 복소수 중 하나이고, 서브셋 내의 적어도 하나의 엔트리

에 대해

인, 동작 방법.6. The method of any one of embodiments 1-4, wherein the selected codebook entry for the case r=2 may be constructed from M=4 distinct variables, each variable being

one of the complex numbers, and at least one entry in the subset

About

In, how it works.

7. A method of operation of a second node (14) connected to a first node (12, 50) in a wireless communication network for reporting multi-beam CSI, the method comprising:

reporting (300A) a rank indicator and a beam count indicator in a first transmission on an uplink control channel; and

Reporting a co-paging indicator in a second transmission on the uplink control channel (302A)

wherein the co-paging indicator identifies a selected entry in the codebook of co-paging coefficients, and wherein the number of bits in the co-paging indicator is identified by at least one of a beam count indicator and a rank indicator.

8. The method of embodiment 7, wherein the beam count indicator comprises at least one of an indication of a beam number and relative powers, wherein possible values of the indication include both zero and non-zero values.

9. A method of operation of a second node (14) connected to a first node in a wireless communication network for reporting CSI, the method comprising:

identifying the number of beams and the index of the beams together in the multi-beam CSI report; and

Transmitting the multi-beam CSI report to the first node (12, 50)

comprising, a method of operation.

10. The method of embodiment 9, wherein identifying the number of beams and the index of the beams together in the multi-beam CSI report comprises:

determining (304A) the number of beams L used to construct a multi-beam CSI report; and

Determining a beam indicator for the first beam (306A)

wherein the beam indicator identifies the index of the beam of the multi-beam CSI report if L is at least l, and identifies that L is less than l otherwise.

11. A method of operation of a second node (14) connected to a first node (12,50) in a wireless communication network, comprising:

when the CSI corresponds to the first rank, reporting the CSI corresponding to the first number of beams (400A); and

If the CSI corresponds to the second rank, reporting the CSI corresponding to the second number of beams (402A)

comprising, a method of operation.

12. The method of embodiment 11, comprising:

the first rank is smaller than the second rank;

and the first number of beams is greater than the second number of beams.

13. The method of any one of examples 1-12,

의 표시를 제공하는 단계를 더 포함하고,At least one beam index pair index in uplink control information (UCI)

further comprising providing an indication of

each pair of beam indexes corresponds to beam k.

14. The method of any one of examples 1-13,

이고, 복소수들의 세트의 각각의 요소는:each beam is a kth beam comprising a set of complex numbers

, and each element of the set of complex numbers is:

characterized by at least one complex phase shift such that

및

는 각각 빔

의 제i 및 제n 요소이며;

and

are each beam

the i and nth elements of ;

은 빔

의 제i 및 제n 요소에 대응하는 실수이고;

silver beam

real number corresponding to the i and nth elements of ;

및

는 정수이며;

and

is an integer;

및

는 복소 위상 시프트

및

를 각각 결정하는 인덱스 쌍

을 갖는 빔들에 대응하는 실수들인, 동작 방법.beam directions

and

is the complex phase shift

and

a pair of indices that each determine

real numbers corresponding to beams with

15. The method as in any one of embodiments 1-14, wherein the first node (12, 50) is a radio access node (12).

16. The method as in any one of embodiments 1-15, wherein the second node (14) is a wireless device (14).

17. A second node (14) adapted to operate according to the method of any one of embodiments 1 to 16.

18. A second node (14), comprising:

at least one processor 20;

memory 22 comprising instructions executable by at least one processor 20

wherein the second node (14) is operable to report to the first node (12,50) rich CSI feedback on the physical channel with a small payload.

19. A second node (14), comprising:

a reporting module (32) operable to report to the first node (12,50) rich CSI feedback on a physical channel with a small payload.

20. A method of operation of a first node (12) in a wireless communication network, comprising:

Receiving (100B) rich CSI feedback from a second node 14 on a physical channel with a small payload

A method of operation comprising a.

21. The method of embodiment 20, wherein reporting the rich CSI feedback comprises:

a step 200B wherein a subset of the codebook is selected from entries from the codebook of coefficients;

a step 202B in which a codebook entry is selected from the subset; and

Receiving an index of the selected codebook entry (204B)

comprising, a method of operation.

22. The method of embodiment 21,

Each entry in the codebook is identified by an index k;

를 포함하고, L' 및 r은 양의 정수이고;An entry in the codebook with index k is a vector or matrix of complex numbers with L' rows and r columns.

wherein L' and r are positive integers;

each (L′-1)r element of each entry contains a scalar complex number that can be one of the N complex numbers;

이고,

는 상이한 코드북 엔트리들의 인덱스들이고,

는 행렬 또는 벡터 C의 프로베니우스 놈이고;

ego,

are indices of different codebook entries,

is the Frobenius norm of a matrix or vector C;

개의 엔트리를 포함하고; the code book

contains entries;

개의 엔트리 중 하나를 포함하고,

및

은 양의 정수이며, 서브셋 내의 각각의 엔트리는 인덱스에 의해 식별되는, 동작 방법.subset is

contains one of the entries,

and

is a positive integer, and each entry in the subset is identified by an index.

에 대해

인, 동작 방법.23. The method of embodiment 22, wherein the selected codebook entry for the case r=2 may be constructed from M=2 distinct variables, each variable may be one of K=N complex numbers, within the subset each entry

About

In, how it works.

24. The method of embodiment 21,

Each entry in the codebook contains a vector or matrix;

one or more elements of each entry include a scalar complex number;

and a norm between a matrix or vector difference between any two different codebook entries is greater than zero.

개의 복소수 중 하나이고, 서브셋 내의 적어도 하나의 엔트리

에 대해

인, 동작 방법.25. The method of any one of embodiments 20-23, wherein the selected codebook entry for the case r=2 may be constructed from M=4 distinct variables, each variable being

one of the complex numbers, and at least one entry in the subset

About

In, how it works.

26. A method of operating a first node (12) in a wireless communication network for reporting multi-beam CSI, comprising:

receiving (300B) a rank indicator and a beam count indicator in a first transmission on an uplink control channel; and

Receiving a co-paging indicator in a second transmission on an uplink control channel (302B)

wherein the co-paging indicator identifies a selected entry in the codebook of co-paging coefficients, and wherein the number of bits in the co-paging indicator is identified by at least one of a beam count indicator and a rank indicator.

27. The method of embodiment 26, wherein the beam count indicator comprises at least one of an indication of the number of beams and the relative powers, wherein possible values of the indication include both zero or non-zero values.

28. A method of operation of a first node (12) connected to a first node in a wireless communication network for reporting CSI, the method comprising:

identifying the number of beams and the index of the beams together in the multi-beam CSI report; and

Receiving a multi-beam CSI report from the second node (14)

comprising, a method of operation.

29. The method of embodiment 28, wherein identifying the number of beams and the index of the beams together in the multi-beam CSI report comprises:

determining (304A) the number of beams L used to construct a multi-beam CSI report; and

Determining a beam indicator for the first beam (306A)

wherein the beam indicator identifies the index of the beam of the multi-beam CSI report if L is at least l, and identifies that L is less than l otherwise.

30. A method of operation of a first node (12) in a wireless communication network, comprising:

if the CSI corresponds to the first rank, receiving CSI corresponding to the first number of beams (400B); and

If the CSI corresponds to the second rank, receiving CSI corresponding to the second number of beams (402B)

comprising, a method of operation.

31. The method of embodiment 30, comprising:

the first rank is smaller than the second rank;

and the first number of beams is greater than the second number of beams.

32. The method of any one of embodiments 20-31,

의 표시를 수신하는 단계를 더 포함하고,At least one beam index pair index in uplink control information (UCI)

further comprising receiving an indication of

each pair of beam indexes corresponds to beam k.

33. The method of any one of embodiments 20-32,

이고, 인덱스 쌍

를 가지며, 복소수들의 세트의 각각의 요소는:each beam is a kth beam comprising a set of complex numbers

, and the index pair

, and each element of the set of complex numbers is:

characterized by at least one complex phase shift such that

및

는 각각 빔

의 제i 및 제n 요소이며;

and

are each beam

the i and nth elements of ;

은 빔

의 제i 및 제n 요소에 대응하는 실수이고;

silver beam

real number corresponding to the i and nth elements of ;

및

는 정수이며;

and

is an integer;

및

는 복소 위상 시프트

및

를 각각 결정하는 인덱스 쌍

을 갖는 빔들에 대응하는 실수들인, 동작 방법.beam directions

and

is the complex phase shift

and

a pair of indices that each determine

real numbers corresponding to beams with

34. The method as in any one of embodiments 20-33, wherein the first node (12, 50) is a radio access node (12).

35. The method as in any one of embodiments 20-34, wherein the second node (14) is a wireless device (14).

36. A first node (12) adapted to operate according to the method of any one of embodiments 20-35.

37. A first node (12, 50) comprising:

at least one processor (36);

memory 38 comprising instructions executable by at least one processor 36 .

wherein the first node (12, 50) is operable to receive rich CSI feedback from the second node (14) on a physical channel with a small payload.

38. A first node (12, 50) comprising:

A first node comprising a receiving module (62) operable to receive rich CSI feedback for a first node (12,50) on a physical channel with a small payload.

The following abbreviations are used throughout this disclosure.

● 1D: 1D

● 2D: 2D

● 3GPP: 3rd Generation Partnership Project

● 5G: 5th generation

● ACK: Acknowledgment

● ARQ: Automatic retransmission request

● ASIC: Application Specific Integrated Circuit

● BPSK: Binary Phase Shift Keying

● CE: Control element

● CPU: Central processing unit

● CQI: Channel quality indicator

● CRI: CSI-RS resource indication

● CSI: Channel state information

● DCI: downlink control information

● DFT: Discrete Fourier Transform

● DL-SCH: Downlink shared channel

● eNodeB: Enhanced or evolved Node B

● EPDCCH: Enhanced PDCCH

● FDD: Frequency division redundancy

● FD-MIMO: full dimension MIMO

● FPGA: Field Programmable Gate Array

● GSM: Global mobile communication system

● HARQ: Hybrid Auto Repeat Request

● LTE: Long Term Evolution

● MAC: Media Access Control

● MCS: Modulation and Coding State

● MIMO: Multiple Input Multiple Output

● ms: milliseconds

● MU-MIMO: Multi-user MIMO

● NACK: negative acknowledgment

● NR: New Radio

● NZP: non-zero power

● OFDM: Orthogonal Frequency Division Multiplexing

● PDCCH: physical downlink control channel

● PMI: Precoder matrix indicator

● PRB: physical resource block

● PUCCH: Physical uplink control channel

● PUSCH: physical uplink shared channel

● QPSK: Quadrature Phase Shift Keying

● RI: rank indicator

● RRC: Radio resource control

● RSRP: Reference signal received power

● RSRQ: Reference signal reception quality

● RSSI: indicator of received signal strength

● SINR: Signal-to-interference and noise ratio

● SR: Scheduling Request

● SRB: signaling radio bearer

● TDD: time division duplication

● TFRE: time/frequency resource element

● TS: Technical Specifications

● UCI: Uplink Control Information

● UE: user equipment

● ULA: Uniform Linear Array

● UL-SCH: Uplink shared channel

● UMB: Ultra Mobile Broadband

● UPA: Uniform Planar Array

● WCDMA: Wideband Code Division Multiple Access

● WiMax: WiMAX (Worldwide Interoperability for Microwave Access)

Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims (1)

A method according to claim 1.

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